• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Panel on underexploited tropical...
 Preface
 Table of Contents
 Introduction and summary
 I. Cereals
 II. Roots and tubers
 III. Vegetables
 IV. Fruits
 V. Oilseeds
 VI. Forage
 VII. Other uses
 Contributors
 Résumé en francais
 Resumen en español
 Advisory committee on technology...
 Advertising
 Back Cover














Group Title: Advisory studies and special reports
Title: Underexploited tropical plants with promising economic value
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00082046/00001
 Material Information
Title: Underexploited tropical plants with promising economic value report of an ad hoc panel of the Advisory Committee on Technology Innovation, Board on Science and Technology for International Development, Commission on International Relations
Series Title: Advisory studies and special reports
Physical Description: ix, 188 p. : ill. ; 23 cm.
Language: English
Creator: National Research Council (U.S.) -- Panel on Underexploited Tropical Plants with Promising Economic Value
United States -- Agency for International Development. -- Office of Science and Technology
Publisher: National Academy of Sciences
Place of Publication: Washington
Publication Date: 1975
 Subjects
Subject: Tropical plants   ( lcsh )
Tropical crops   ( lcsh )
Botany, Economic -- Tropics   ( lcsh )
Botanica   ( larpcal )
Agricultura -- Aspectos económicos
Plantes tropicales   ( rvm )
Botanique agricole   ( rvm )
Plantes comestibles   ( rvm )
Países subdesarrollados
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
General Note: "Prepared ... for the Office of Science and Technology, Bureau for Technical Assistance, Agency for International Development, Washington, D.C."
General Note: Summary in French and Spanish.
 Record Information
Bibliographic ID: UF00082046
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 04134947
lccn - 78307251

Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Title Page
        Page i
        Page ii
    Panel on underexploited tropical plants with promising economic value
        Page iii
        Page iv
    Preface
        Page v
        Page vi
        Page vii
    Table of Contents
        Page viii
        Page ix
        Page x
    Introduction and summary
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    I. Cereals
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    II. Roots and tubers
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
    III. Vegetables
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
    IV. Fruits
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
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        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
    V. Oilseeds
        Page 89
        Page 90
        Page 91
        Page 92
        Page 93
        Page 94
        Page 95
        Page 96
        Page 97
        Page 98
        Page 99
        Page 100
        Page 101
        Page 102
        Page 103
        Page 104
        Page 105
        Page 106
        Page 107
        Page 108
        Page 109
        Page 110
    VI. Forage
        Page 111
        Page 112
        Page 113
        Page 114
        Page 115
        Page 116
        Page 117
        Page 118
        Page 119
        Page 120
        Page 121
        Page 122
        Page 123
        Page 124
        Page 125
        Page 126
        Page 127
        Page 128
        Page 129
        Page 130
        Page 131
        Page 132
    VII. Other uses
        Page 133
        Page 134
        Page 135
        Page 136
        Page 137
        Page 138
        Page 139
        Page 140
        Page 141
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        Page 167
        Page 168
    Contributors
        Page 169
        Page 170
        Page 171
        Page 172
    Résumé en francais
        Page 173
        Page 174
        Page 175
        Page 176
        Page 177
        Page 178
    Resumen en español
        Page 179
        Page 180
        Page 181
        Page 182
        Page 183
        Page 184
    Advisory committee on technology innovation and board on science and technology for international development
        Page 185
        Page 186
    Advertising
        Page 187
        Page 188
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text
















































7












Underexploited
Tropical Plants
with Promising
Economic Value



Report of an Ad Hoc Panel of the Advisory
Committee on Technology Innovation
Board on Science and Technology for
International Development
Commission on International Relations

Avec r6sum6 en frangais
Con resume en espafiol




NATIONAL ACADEMY OF SCIENCES
Washington, D.C. 1975













































This report has been prepared by an ad hoc advisory panel of the Board on Science and
Technology for International Development, Commission on International Relations,
National Research Council, for the Office of Science and Technology, Bureau for
Technical Assistance, Agency for International Development, Washington, D.C., under
Contract No. csd-2584.
NOTICE: The project that is the subject of this report was approved by the
Governing Board of the National Research Council, whose members are drawn
from the Councils of the National Academy of Sciences, the National Academy
of Engineering, and the Institute of Medicine. The members of the Committee
responsible for the report were chosen for their special competence and with
regard for appropriate balance.
This report has been reviewed by a group other than the authors according
to procedures approved by a Report Review Committee consisting of members
of the National Academy of Sciences, the National Academy of Engineering, and
the Institute of Medicine.

Illustrations by Elmer W. Smith, Cambridge, Massachusetts.




Second Printing, September 1976



ii










PANEL ON UNDEREXPLOITED TROPICAL PLANTS
WITH PROMISING ECONOMIC VALUE

EDWARD S. AYENSU, Chairman, Department of Botany, Smithsonian
Institution, Washington, D.C., Cochairman
RICHARD E. SCHULTES, Director, Botanical Museum of Harvard Univer-
sity, Cambridge, Massachusetts, Cochairman
HERBERT G. BAKER, Department of Botany, University of California,
Berkeley, California
JACQUES BARRAU, Laboratoire d'Ethnobotanique, Jardin des Plantes,
Paris, France
J. P. M. BRENAN, Deputy Director, Royal Botanic Gardens, Kew, Surrey,
England
H. C. D. deWIT, Laboratory for Plant Taxonomy and Geography, University
of Agriculture, Wageningen, The Netherlands
SELWYN L. EVERIST, Director, Botanic Museum and Herbarium, Botanic
Gardens, Indooroopilly, Queensland, Australia
ALVARO FERNANDEZ PEREZ, Instituto de Ciencias Naturales de la
Universidad Nacional, Bogota, Colombia
CHARLES B. HEISER, Department of Botany, Indiana University, Bloom-
ington, Indiana
S. E. MALO, Agricultural Research and Education Center, Homestead,
Florida
FRANKLIN MARTIN, Federal Experiment Station, Mayagiiez, Puerto Rico
WALTER B. MORS, Centro de Pesquisas de Produtos Naturais, Instituto de
Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Rio de
Janeiro, Brazil
JULIA MORTON, Morton Collectanea, University of Miami, Coral Gables,
Florida
PETA MUDIE, University of California, Scripps Institution of Oceanography,
La Jolla, California
ROBERT RAFFAUF, College of Pharmacy, Northeastern University, Boston,
Massachusetts
WERTIT SOEGENG REKSODIHARDJO, Pioneer Hi-bred International Inc.,
Chinandega, Nicaragua
JONATHAN SAUER, University of California at Los Angeles, Los Angeles,
California
JOEL SCHECHTER, Director, Research and Development Authority, Ben-
Gurion University of the Negev, Beer-Sheva, Israel
WILLIAM H. STAHL, Research Manager, McCormick and Company, Re-
search and Development Laboratories, Hunt Valley, Maryland









ROY WHISTLER, Department of Biochemistry, Purdue University, Lafay-
ette, Indiana
NOEL D. VIETMEYER, Board on Science and Technology for International
Development, Commission on International Relations, National Academy
of Sciences-National Research Council, Staff Study Director




JULIEN ENGEL, Board on Science and Technology for International
Development, Commission on International Relations, National Academy
of Sciences, National Research Council, Head, Special Studies









PREFACE


This is a report on plants that show promise for improving the quality of life
in tropical areas. Because the countries in this zone contain most of the
world's low-income populations this report is addressed to those government
administrators, technical assistance personnel, and researchers in agriculture,
nutrition, and related disciplines who are concerned with helping developing
countries achieve a more efficient and balanced exploitation of their
biological resources.
The ad hoc panel on underexploited tropical plants, which produced the
report, met at Airlie, Virginia, in March 1974. The panel had the following
objectives:
To identify neglected but seemingly useful tropical plants, both wild
and domesticated, that have economic potential;
To select the plants that showed the most promise for wider
exploitation throughout the tropics; and
To indicate requirements and avenues for research to ensure that
selected plants reach their fullest potential.
The 36 plants described here were selected from among 400 nominated by
plant scientists around the world in response to a written inquiry. (To keep
the project to manageable size, medicinal plants and timber species were
excluded.) The choice reflected here is necessarily subjective, based as it is on
the experience and judgment of the panel. Plants chosen for inclusion had to
satisfy several criteria, the most important of which were:
Can it be grown in the tropics?
Does it have significant potential as a source of food, forage, or
industrial raw material?
Can it help make developing countries (or areas within them) more
productive?
Other considerations were: Can the plant make a specific contribution to
human nutrition? Does the plant have multiple properties enabling several
useful products to be obtained from it? The plants were not judged solely by
how much or how little is known about them, however. Some of the plants
selected are relatively well known; others are taxonomically not yet fully
described. Some are "luxury crops" that will appeal only to high-priced
specialty markets; others are subsistence crops.
Since it is impossible to determine future costs and benefits of exploiting
these plants in vastly dissimilar economic environments, selection could not
be based on economic considerations except in the most informal and
subjective manner. The task of weighing the technical details against the
economics, needs, resources, and capabilities of a particular country or area is
perforce left to interested, competent authorities.










The panel recognizes that some plants recommended but finally not
selected for inclusion in this report may well have similar potential for
exploitation. In such cases, the panel did not have, and could not obtain,
enough information to support an affirmative decision.
The plants presented here should be seen as complements to, not as
substitutes for, conventional tropical crops.
The report aims to provide a brief introduction to the plants selected. It is
neither a textbook nor a comprehensive survey of tropical botany. For the
convenience of the reader, each plant is presented in a separate chapter,
arranged in the following order:

Description of the plant and of its advantages
Limitations and special requirements
Research needs
Selected readings (significant reviews, general articles)
Research contacts and germ plasm sources (individuals or organizations
known by the panelists to be involved in relevant research or to have
appropriate seeds, cuttings, or rootstock).

This report does not detail how to introduce the plants to new areas.
Readers should appreciate that achieving this goal may be complex and
difficult. Many plants discussed in this report have defied dissemination (or
domestication) for a century or more. Plant introduction cannot be divorced
from plant management; a lack of horticultural knowledge or experience will
frequently cause a plant introduction to fail. Differences in elevation, soil
type, temperature, day length, and rainfall present other complications.
Sometimes newly introduced plants prove to be too aggressive and become
weeds. Even if all these problems are overcome, the plant will be successful
only if a market exists or can be created for its products.
The information in this book is only a starting point for what may prove
to be laborious and troublesome projects. Addresses of knowledgeable
contacts are provided so that readers may ascertain for themselves specific
details that cannot be covered in a general report of this kind, but that may
be critical to the successful introduction of a plant to their locality.
The panel felt that certain points on the status of tropical botany and the
urgency of preserving germ plasm were so important that, although not part of
the panel's formal mandate, they are discussed in Chapter 1.
The panel is indebted to the contributors (listed on page 169) and to
Mary Jane Koob, who acted as administrative secretary for the meeting and
for production of the report. The manuscript was edited and prepared for
publication by F. R. Ruskin.










Comments on this report, especially if it has induced initiatives or further
research on the species described, should be communicated to the staff
officer, Dr. Noel Vietmeyer, National Academy of Sciences-National Re-
search Council, 2101 Constitution Avenue, JH215, Washington, D.C. 20418,
USA. Suggestions and information from readers about species not covered in
this volume are welcome. They might be included in a later publication.








CONTENTS


Introduction and Summary


I CEREALS 9

Echinochloa turnerana 9
Grain Amaranths 14
Quinua 20
Zostera marina 24


H ROOTS AND TUBERS 29

Arracacha 29
Cocoyams 33
Taro 37


III VEGETABLES 45

Chaya 45
Hearts of Palm 48
Wax Gourd 53
Winged Bean 56


IV FR UITS 63


Durian
Mangosteen
Naranjilla
Pejibaye
Pummelo
Soursop
Uvilla








V OILSEEDS 89

Babassui Palm 89
Buffalo Gourd 94
Caryocar Species 100
Jessenia polycarpa 103
Jojoba 105


VI FORAGE 111

Acacia Albida 111
Brosimum alicastrum 114
Cassia sturtii 118
Saltbushes 122
Tamarugo 128


VII OTHER USES 133


Buriti Palm
Calathea lutea
Candelilla
Guar
Guayule
Paspalum vaginatum
Ramie
Spirulina


Contributors


R6sum6 en frangais 173
Resumen en espafiol 179'
Advisory Committee on Technology Innovation 185
Board on Science and Technology for International Development 185
BOSTID Publications 187









INTRODUCTION AND SUMMARY


The strain on world resources posed by rapid population growth, dwindling
supplies of nonrenewable resources, and shortages of food puts economic
botany in the mainstream of human concern.
Throughout history man has used some 3,000 plant species for food; at
least 150 of them have been commercially cultivated to some extent. But
over the centuries the tendency has been to concentrate on fewer and fewer.
Today, most of the people in the world are fed by about 20 crops-cereals
such as wheat, rice, maize, millet, and sorghum; root crops such as potato,
sweet potato, and cassava; legumes such as peas, beans, peanuts groundnutss),
and soybeans; and sugar cane, sugar beet, coconuts, and bananas. These plants
are the main bulwark between mankind and starvation. It is a very small
bastion.
Yet as the prospect of food shortages becomes more acute, people must
depend increasingly on plants rather than animals for the protein in their diet.
As is well recognized, research is urgently needed to increase the yield of
these food plants. However, reliance on a small number of plants carries great
risk, for monocultures are extremely vulnerable to catastrophic failure
brought about by disease or variations in climate. To help feed, clothe, and
house a rapidly increasing world population, it is timely to consider neglected
or little-known plant species.
Man has only just begun to take stock of the chemical and genetic
possibilities in the plant kingdom. Now we must scrutinize the thousands of
plant species, many of which are still untested and some as yet unidentified.
The apparent advantages of staple plants over minor tropical plants often
result only from the disproportionate research attention they have been
given. Many indigenous species may possess equal merit, but were disregarded
during the colonial era when consumer demands in European countries
largely determined the cultivation (and research) priorities in tropical
agriculture. The crops selected (such as banana, pineapple, Hevea [rubber],
African oil palm, coconuts, and groundnuts) received considerable research
and extension. Even after independence, the pattern of concentrating on a
few crops changed little. Markets abroad were established, and the new
countries needed foreign exchange. Furthermore, as indigenous scientists
were generally trained in the institutions of temperate-zone countries they
had little interest in studying tropical species. Even the food preference of
local populations in tropical colonial countries became so influenced by
European food habits that in many places local demand for traditional crops
declined.







UNDEREXPLOITED TROPICAL PLANTS


Because of these factors, the potential of many tropical crops has never
been explored. A striking case is quinua,* one of the most productive sources
of plant protein. It grows high in the Andes, where few other crops can
survive. The Spanish introduced wheat and barley and focused agricultural
research only on those crops, which eventually displaced quinua. Despite its
intrinsic nutritive and economic value and the fact that protein deficiency is a
serious problem in its native region, the agronomy of quinua has advanced
little in the past four centuries.


TROPICAL PLANT RESOURCES

Most agricultural scientists are unaware of the scope and potential offered by
tropical botany. The discipline suffers largely because the major centers of
scientific research are located in temperate zones.
There is an urgent need for plant researchers to become acquainted with
tropical plant life. Important new products-such as oils, gums, and waxes for
industry; proteins for food and feed; and chemicals for pest control-are
likely to result from their attention.
The variety of tropical plant species is staggering. Contained among them
is a wealth of new products. In studying tropical economic botany it is not
enough to consider solely traditional needs and markets. New raw materials
also will be required in the future. Changing conditions are already creating
demands for new products from previously underexploited plants; more will
be needed as pressures increase for the exploitation of renewable resources.
Innovations in transportation already make it feasible to transport
perishable products around the world.
Affluence in certain parts of the world has enhanced the consumer's
ability to pay for specialty items and heightened his desire for new products
such as rare spices, fruit, and fragrances.
Paradoxically, burgeoning population and continued poverty elsewhere
are increasing the need for survival plants and for those hardy species that can
be grown in unusable, marginal land.
Improved scientific knowledge of adverse effects of certain products
has created demands for new products, including unsaturated fats, low-calorie
sweeteners, and biodegradable pesticides.
New industrial processes have stimulated the need for larger supplies of
materials such as elastomers, lubricating oils, drug-precursors, and waxes.
Tropical plants appear able to meet many of these demands. Given
concentrated research, many underexploited plants could follow the develop-


*See page 20.







INTRODUCTION AND SUMMARY


mental course of the soybean. During the past 50 years the rising need for
protein has turned the soybean into a staple in many parts of the world,
including the United States, where the plant was once an oddity.


PRESERVATION OF PLANT GERM PLASM

A massive effort is needed to ensure the survival of endangered plant species
throughout the world. It comes as a surprise to most non-botanists to learn
that one out of every 10 plants is either extinct or in imminent danger of
extinction. Over 20,000 species are now in need of protection. Wanton
destruction of natural vegetation is killing many, but the relentless spread of
conventional agriculture displaces and destroys many others. Careful preserva-
tion and thorough cataloguing are particularly important for little-known
plants such as those described in this report. Only in this way will the genetic
diversity and healthy stock needed for developing new food crops be assured.
Potential breeding stocks, clones, and cultivars will otherwise become extinct.
To this end, the number of botanic gardens, field stations, and habitat
reserves containing natural vegetation types must be increased. At present,
the number is actually decreasing: rising costs and urban sprawl are making it
more difficult for local botanic gardens in tropical countries to survive. And
with their demise even existing collections of tropical germ plasm are being
lost. To save these service centers and botanic gardens in the tropics, financial
support is urgently required. Local governments must be made more aware of
the importance of their native flora resources to their country's economic
development and of the need to inventory, maintain, and capitalize on their
indigenous vegetative materials. The Stockholm Conference on the Human
Environment of 1973 recognized this imperative in its proposal for the
establishment of an international network of genetic resource stations. The
concept is strongly endorsed by the panel.
The number of personnel trained in tropical plant science must also be
increased. Today, few institutions in the world offer training in tropical
botany, tropical horticulture, and tropical agronomy. Facilities for training
and research should be established rapidly because the time left for the study
of undisturbed tropical vegetation is limited.


PLANT INTRODUCTION

Agriculture in the tropical world suffers for lack of mechanisms for
systematically and routinely introducing and investigating little-known but
potentially useful tropical plants. Because most tropical countries are poor,







UNDEREXPLOITED TROPICAL PLANTS


their experiment stations cannot afford to devote time and money to
lesser-known plants. To alleviate this problem, development agencies and
foundations concerned with agriculture should consider sponsoring a system
of horticultural facilities (in tropical and subtropical developing countries) to
pursue agronomic research and extension on lesser-known indigenous and
newly introduced species. In part, such facilities could be extensions of the
network of international agricultural research institutions already in
existence.

A summary of the plants selected by the panel for their high promise follows.


Cereals and Pseudocereals

Echinochloa turnerana. This wild Australian grass, which has never been
studied, yields nutritious grain with just one deep watering. It has important
potential for dry land farming in arid regions with sporadic rainfall.
Grain Amaranths (Amaranthus species). The seeds of these almost totally
neglected Central American grain crops have extremely high levels of protein
and of the nutritionally essential amino acid, lysine, which is usually deficient
in plant protein.
Quinua (Chenopodium quinoa). Although the seed of this tall herb is one
of the best sources of protein in the vegetable kingdom, quinua is not
cultivated outside its high-altitude Andean home.
Zostera marina. Exploratory research on this plant might uncover
important benefits, for it is a grain-producing, grass-like plant that grows in
seawater. Using the sea to grow grain is a novel and highly speculative
concept, but Indians on Mexico's west coast have traditionally harvested
Zostera marina grain for food and flour.


Roots and Tubers*

Arracacha (Arracacia xanthorrhiza). Known as Peruvian parsnip because of
the taste and texture of its root, this plant, which looks like celery, is
little known outside the highlands of the Andes. In this region its root is of-
ten grown instead of potato and costs only half as much to produce. Arraca-
cha has unrealized potential in tropical highlands worldwide.

*Yams (Dioscorea spp.). Although yams are too well known for inclusion in this report
they are the most nutritious and popular of the conventional, tropical root crops.
Nevertheless, they are not so widely cultivated as some of their competitors because they
are more costly to produce; research to reduce production costs would be extremely
valuable. Research on storage problems is also urgently needed: often 60 percent of the
yams harvested are lost to rot.







INTRODUCTION AND SUMMARY


Cocoyams (Xanthosoma spp.). These highly productive root crops are
more nutritious than cassava and quite easily produced. Although they are
widely distributed, they never have been subjected to a comprehensive
improvement program and they appear to have much unrealized potential.
Taro and Dasheens (Colocasia esculenta). Intensively cultivated in only a
few countries, the high-yielding taro has worldwide tropical potential. Some
types grow upland, others grow in waterlogged, swampy soils that otherwise
are unproductive. Dasheens are Asian varieties that produce many small, crisp
corms that store well.


Vegetables
Chaya (Cnidoscolus aconitifolius and Cnidoscolus chayamansa). The leaves of
these fast-growing, prolific shrubs are a nutritious, spinach-like, green
vegetable. Known only in Central America, chaya deserves testing elsewhere
in the tropics.
Hearts of Palm (harvested from Euterpe, Bactris, Acrocomis, Cocos palms,
etc.). The demand for this delicacy has increased so rapidly during the past 10
years that current supplies are inadequate. Wild stands are being harvested
relentlessly. Since extracting the heart kills the palm, plantation cultivation
(which appears highly promising economically) must be encouraged before
wild stands are destroyed.
Wax Gourd (Benicasa hispida). This large, melon-like vegetable is easy to
grow and can yield three crops per year. Its outstanding feature is that the
fruit can be kept without refrigeration for as long as 12 months.
Winged Bean (Psophocarpus tetragonolobus). This climbing bean, im-
portant in Southeast Asia and Papua New Guinea but unknown elsewhere, is
possibly the tropical counterpart of the soybean. With research, it could
perhaps become one of the best sources of usable protein in the tropics.


Fruits
Durian (Durio spp.). The common durian is a large, spiny fruit that is
esteemed by many for its taste and reviled by others for its odor. Newly
discovered odorless species might be more aesthetically acceptable and could
open a world market for this crop.
Mangosteen (Garcinia mangostana). Perhaps the world's best-tasting fruit,
the mangosteen is little known outside its Southeast Asian habitat.
Concentrated agronomic and horticultural research would help extend its
range to other parts of the very humid tropics-a climate zone that is unsuited
to most crops.







UNDEREXPLOITED TROPICAL PLANTS


Naranjilla (Solanum quitoense). Related to, but wholly unlike, tomatoes,
this dessert fruit is highly esteemed in Peru, Colombia, Ecuador, and
Guatemala, but virtually unknown elsewhere. Its delicious, refreshing juice
might become popular in the African and Asian tropics, where the plant could
easily flourish.
Pejibaye (Guilielma gasipaes). The chestnut-like fruit of this palm is
probably the most nutritionally balanced of tropical foods. It contains
carbohydrates, protein, oil, minerals, and vitamins. Suited to the wet tropics,
the trees, once established, require little care and yield well.
Pummelo (Citrus grandis). This large fruit, probably a parent of the
grapefruit, is highly prized throughout Southeast Asia. Superior cultivars
would become important crops if produced elsewhere in the lowland tropics.
Though widely tested in the citrus regions of the world, the cultivars tested
never approached the quality of the best from southern Thailand.
Soursop (Annona muricata). Well known in the South and Central
American tropics, the rich, aromatic flavor of soursop pulp could be more
widely enjoyed. The fruit pulp and juice keep well and are potentially
profitable exports to Europe and North America.
Uvilla (Pourouma cecropiaefolia). This grape-like fruit is almost unheard of
outside its homeland in the western part of the Amazon basin. Its agreeable
pulp is eaten raw and is also made into wine. It merits trial in other forested
lowland regions of the tropics. Absolutely nothing is known about its
cultivation or agronomic potential.


Oilseeds
Babassfi (Orbignya speciosa). This palm grows in abundance in the Amazon
basin and parts of Central America. Though the seeds are rich in oil (very
similar to coconut oil in composition), the babassfi palm has not been
domesticated. The main barriers to its exploitation are the labor required for
seed collection and the fact that the extremely hard seeds are difficult to
open.
Buffalo Gourd (Curcurbita foetidissima). This wild, North American desert
gourd, which furnished edible seeds for the American Indians, is a potentially
profitable source of edible oil and protein in extremely arid lands. It deserves
wider recognition and test planting in all arid regions of the world.
Caryocar species. Although Sir Henry Wickham, the initiator of the
Malayan rubber industry, promoted this oil source as enthusiastically as he
did the rubber tree, Caryocar species remain little-known trees growing wild
in the Amazon region. They bear large quantities of oily seeds resembling
Brazil nuts.







INTRODUCTION AND SUMMARY


Jessenia polycarpa. Native to the Amazon region, this palm bears
extraordinarily large bunches of fruit with an oil similar to olive oil in
appearance, composition, and quality. It is sold as an edible oil in Bogoti,
Colombia, but is virtually unknown to the rest of the world.
Jojoba (Simmondsia chinensis). This subtropical, North American desert
plant is unique in the vegetable kingdom; it secretes liquid wax in its seeds
instead of the glyceride oils secreted by other plants. Liquid waxes are
important in industry. They are difficult to synthesize, and the only other
source is the sperm whale. The development of jojoba as a crop promises to
provide important economic benefits to arid tropical and subtropical regions.

Forage Crops
Acacia Albida. Occurring in savannas of East and West Africa, this leguminous
tree is unusual in that it is verdant with foliage and fruit during the dry
season. Its leaves and pods, relished by all kinds of livestock, are often the
only fodder available at that time.
Brosimum alicastrum. This tall, drought-resistant tree bears nutritious
leaves and small fruit with starchy seeds. The foliage is enjoyed by livestock.
Little known outside Central America, it deserves testing in tropical
areas-especially those having prolonged dry seasons-where a forage source is
needed.
Cassia sturtii. Considered unimportant as forage in its native Australia,
this bush is providing nutritious forage year-round in experimental projects
in Israel. Its potential needs to be determined in other arid regions of
temperate or subtropical climate.
Saltbushes (Atriplex spp.). Several Australian species of these shrubs show
great promise for arid regions. They produce an abundance of palatable
forage, especially in saline soils.
Tamarugo (Prosopis tamarugo). A hardy, leguminous tree, native to the
forbidding Atacama Desert in Chile, tamarugo grows through a layer of salt
sometimes 1 m thick. The nutritional quality of its pods and leaves allows
sheep to be stocked at rates approaching those of the best forage areas in the
world.


Other Uses
Buriti Palm (Mauritiaflexuosa). Perhaps the most plentiful palm in the world,
the buriti is not commercially used. Yet many products-starch, fruit, fiber,
and wood-could be obtained from it on a large scale. In the Amazon basin,
its native home, it is a plentiful resource that would well repay research and







UNDEREXPLOITED TROPICAL PLANTS


development. There are comparable palms elsewhere in the tropics that
should be similarly investigated.
Calathea lutea. This tall herb grows wild in swamps in the Amazon
basin, but does equally well in plantations in wet regions. Its leaves are
coated with a hard-melting wax. Simple to plant and harvest, Calathea
lutea could provide jobs and income in otherwise unusable tropical
swamps.
Candelilla (Euphorbia antisyphilitica). This herb from the deserts of
northern Mexico has leaves coated with valuable wax. A subsidized Mexican
industry has produced and exported it to the United States for several years.
Research into the processing and cultivation of candelilla could convert it
into a highly profitable crop for arid lands throughout the subtropics.
Guar (Cyamopsis tetragonoloba). The high-protein seeds of this Asian
plant, which resembles the soybean, contain a gum that is in increasing
demand by industry. Because of its unusual properties, the gum has many
uses, from making water slide more readily through fire hoses to thickening
ice cream. Of all sources for vegetable gums, guar is the most promising.
Guayule (Parthenium argentatum). A shrub of Mexican deserts, guayule
contains good quantities of latex that closely resembles that from the Hevea
rubber tree. Technical problems associated with separating the latex from
resins and other vegetable matter have prevented its development. But it still
holds great promise and, given research, it could become an important source
of rubber for production in arid lands.
Paspalum vaginatum. This highly salt-tolerant grass withstands inundation
by seawater and is recommended for the revegetation of salt-affected
regions. It is especially good for stabilizing sandy beaches. Already
cultivated successfully in Australia, it provides forage in otherwise unusable
coastal marshes.
Ramie (Boehmeria nivea). The fiber from this tall, perennial shrub, native
to East Asia, has superior qualities-strength and freedom from stretch and
shrinkage among others. But its use is restricted by the sticky gum that clings
tenaciously to the fiber. Solving the problem of degumming (without
weakening the fiber) would give ramie a significant role in tropical
agriculture.
Spirulina (Spirulina platensis and Spirulina maxima). These high-protein
algae grow in brackish and alkaline waters. Unlike some other algae,
spirulina's large aggregations make it easy to harvest by net or other simple
means. It is palatable and is already eaten in Chad and Mexico.










I CEREALS






ECHINOCHLOA TURNERANA

Echinochloa turnerana,* a little-known wild Australian plant, has never been
used directly by man, nor has the possibility of cultivating it been
investigated. Nevertheless, it offers great promise as a forage and grain crop
for arid regions. Its most significant feature is that only a single watering is
required for the plant to develop from germination to harvest.
Locally called channel millet, channel sorghum, and native sorghum, it
grows almost exclusively in the channel country of inland Australia (see map,
p. 11) where it is recognized as one of the most palatable, nutritious, and
productive fodder grasses. The grain is eaten by horses, cattle, and sheep and
is much sought after by native birds. In addition the leaves, culms, and seed-
heads are readily eaten by livestock. Furthermore, the whole plant makes
excellent hay.
Field experience indicates that the seed of Echinochloa turnerana will not
germinate after light rains; deep flooding is required. Deep floods not only
induce germination, but allow the plant to complete its development without
further water. So, unlike other cereals, it does not require a series of
waterings throughout its lifetime.
Echinochloa turnerana always grows in fertile, silty clay that cracks deeply
when dry and is sporadically subjected to deep flooding. Sites may remain
dry for years between floodings. The plant often grows abundantly during
spring, summer, or early autumn when floods occur.
Echinochloa inundata, similar in appearance and growth habits to
Echinochloa turnerana, has only recently been identified as a distinct species.
It grows in less arid areas than Echinochloa turnerana: in swamps and clay
soil depressions (that hold water for several weeks after heavy rain), and along
streams and ponds. Collectors' notes indicate that it, too, is palatable to
livestock, but its nutritional value is unknown.

*Echinochloa turnerana (Domin) J.M. Black. Family: Gramineae.







UNDEREXPLOITED TROPICAL PLANTS


Echinochloa turnerana. (R. G. Silcock)


LIMITATIONS AND SPECIAL REQUIREMENTS

Almost nothing is known about the agronomy or use of Echinochloa
turnerana. No attempts have yet been made to domesticate it, and there is
little documented information on its botany, germination, growth, environ-
mental requirements, yield, etc.







CEREALS


\TASMANIA








Echinochloa turnerana. Known as channel millet, this wild cereal grows in Central
Australia's channel country, shown here. This arid region receives an average of 100mm
of rain annually, which falls irregularly in only one or two downpours.


Some species of Echinochloa are ruinous rice field weeds. The Echinochloa
crus-galli complex contains some of the weeds most feared by rice growers.
The weediness of Echinochloa turnerana is unknown, but strict quarantine
measures must be enforced during experiments in case it is like its relatives.











































In river beds and low-lying regions, Echinochloa turnerana grows prodigiously after the soil has been thoroughly soaked. It needs only a single
watering to complete its life cycle-an important benefit in arid areas where rainfall is irregular. (S. L. Everist)










.5-


Although it is a wild plant never subjected to agronomic improvement, Echinochloa turnerana
bears dense and heavy seed heads. (S. L. Everist)


N'






UNDEREXPLOITED TROPICAL PLANTS


RESEARCH NEEDS

A large collection of seeds is needed for study and distribution and for testing
in suitable tropical and subtropical arid and semi-arid lands.
The requirements for germination, growth, and optimum production must
be determined.
The genetic behavior (particularly genetic variability and possibilities for
selection and breeding of superior strains from wild populations) must be
investigated.
Testing with available seed- and forage-harvesting equipment and grain-
cleaning equipment should be conducted in Australia.


Selected Readings
Black, J. M. 1943. Flora of South Australia. Part 1, 2nd Ed. Government Printer,
Adelaide, Australia. p. 72.
Blake, S. T. 1938. Proceedings of the Royal Society of Queensland. 49:187.
Skerman, P. J. 1947. Bureau of investigation technical bulletin number 1. In The
Channel Country of South-west Queensland. pp. 71-92. Queensland Department of
Public Lands, Brisbane, Australia.

Research Contacts and Germ Plasm Supply
Department of Agronomy, University of Sydney, Sydney, New South Wales 2006,
Australia (P. A. Michael)
Director of Agriculture, Department of Primary Industries, William Street, Brisbane,
Queensland 4000, Australia
Queensland Herbarium, Meiers Road, Indooroopilly, Queensland 4068, Australia (S. L.
Everist, Director)







GRAIN AMARANTHS


Three promising species of Amaranthus* are largely neglected candidates for
increasing protein production in developing countries. Amaranths are
fast-growing, cereal-like plants that produce high-protein grains in large,
*1. Amaranthus caudatus L. (Amaranthus edulis Speg. is considered a race of this
species), 2. Amaranthus cruentus L., and 3. Amaranthus hypochondriacus L. (also
known asAmaranthus leucocarpus). Family: Amaranthaceae.







CEREALS


Amaranthus hypochondriacus. (Rodale Press, Inc.)


sorghum-like seed heads. Their protein-rich leaves are already widely con-
sumed (a tropical spinach that can be harvested many times a year).
Analyses and feeding experiments demonstrate that Amaranthus edulis
grain is rich in protein and exceptionally high in lysine-one of the critical
amino acids usually deficient in plant protein. In Amaranthus edulis 6.2 g
lysine per 100 g protein has been measured.* This value exceeds that found
in high-lysine maize varieties (opaque-2 and floury-2) even in milk. It is
about the same as that found in soymeal.
The seeds of all three species are high in protein. Amaranthus hypochon-
driacus seed contains about 15 percent protein and 63 percent starch. The
starch is similar to the premium-priced starch of waxy maize.t
These amaranths are now cultivated as minor grain crops in Latin America:
Amaranthus caudatus in the Andean regions of Argentina, Peru, and Bolivia;
Amaranthus cruentus in Guatemala; and Amaranthus hypochondriacus in
Mexico. They are ancient crops, which at the time of the Conquest were
major grain crops in tropical highlands of the Americas. Displaced by
larger-seeded grains such as maize, they were relegated to secondary, often
inconspicuous, roles. Cultivation of Amaranthus hypochondriacus was also

*W. J. S. Downtown. 1973. See Selected Readings.
tibid.







UNDEREXPLOITED TROPICAL PLANTS


suppressed by the Spanish church in its effort to eradicate pagan Aztec
ceremonies that centered around amaranths. For over a century, grain
amaranths have been important to Asian hill tribes, and their use is spreading
into the plains of India.
Amaranth grain is usually parched and milled and the dough formed into
pancakes, or it may be cooked for gruel, popped and made into confections,
or powdered and made into a drink. Young plants are often gathered as
potherbs.
Although little accurate information is available on amaranth grain yield,
the crop is reported to show a greater yield than maize grown on adjacent
plots. A harvest of about 1 ton per hectare has been reported for Amaranthus
hypochondriacus cultivated in Gujarat State in India.


LIMITATIONS AND SPECIAL REQUIREMENTS

The amaranths grown for grain are pale seeded. The appearance, flavor, and
popping capability of the pale seeds are best. Wild, dark-seeded varieties are
those generally used as potherbs and ornamentals; they are not suitable for
grain. Dark seeds should be culled before planting because they often produce
vigorous, weedy plants.
Amaranths require good, well-tilled soil and moderate rainfall. Seed may
be broadcast, and the seedlings thinned (thinnings make good potherbs), or
transplanted out as nursery-grown plants. Each plant requires about as much
room as a large maize plant. They probably require large amounts of nitrogen
and phosphorus.
The huge seed heads must be cut when the seed begins to ripen and fall.
Threshing and winnowing require hand labor.
Each of the three Amaranthus species grows in a wide range of climates,
but local varieties differ in their day-length responses: experimentation is
required to find varieties best suited to a given location.


RESEARCH NEEDS

Because of the importance of the discovery of high lysine in Amaranthus
edulis, the composition and nutritive potential of varieties of the other
Amaranthus species should be evaluated by nutritionists.
Investigation of the preparation of the seed (and derived products)
into acceptable dishes should be initiated. Processing losses and pre-
servation methods for commercial and home use should be considered.
Particular emphasis should be placed on labor requirements, rotation
and cropping patterns, and comparisons with other crops grown in the same






CEREALS


The seed head ofAmaranthus hypochondriacus. (Rodale Press, Inc.)


;1. -
1
----


~Pa,


9~B-~

































































Harvesting heavily laden Amaranthus hypochondriacus. (Rodale Press, Inc.)








CEREALS


region. A detailed study of the traditional cultivation, harvesting, processing,
and use of grain amaranths in Latin America and India's highland regions is
necessary.
Since seed shedding (shattering) is a problem, an effort should be made to
discover nonshattering varieties.
As in soybeans, the onset of grain amaranth flowering depends on day
length (photoperiod). Races should be selected for different latitudes and
rainfall regimes.
Accurate records of yield are needed for different agronomic treatments
and in different climatic regions.
Seed size may have important influence on seed composition (for example,
the ratio of husk to endosperm) and hence on seed quality. Seed size,
therefore, warrants special agronomic attention.


Selected Readings
Downtown, W. J. S. 1973. Amaranthus edulis: a high lysine grain amaranth. World Crops.
25(1):20.
MacMasters, M. M., P. D. Baird, M. M. Hazapfel, and E. C. Rist. 1955. Preparation of
starch from Amaranthus cruentus seed. Economic Botany. 9(3):300-2.
Safford, W. E. 1917. A forgotten cereal of ancient America. Proceedings 19th
International Congress of Americanists, 1915. Washington, D.C. pp. 286-97.
Sauer, J. D. 1950. The grain amaranths: a survey of their history and classification.
Annals of the Missouri Botanical Garden. 37: 561-632.
Sauer, J. D. 1967. The grain amaranths and their relatives; a revised taxonomic and
geographic survey. Annals of the Missouri Botanical Garden. 54:103-37.
Singh, H. 1962. Grain Amaranths, Buckwheat and Chenopods. Indian Council of
Agricultural Research, New Delhi.


Research Contacts and Germ Plasm Supply
Asian Vegetable Research and Development Center, P.O. Box 42, Shanhua, Tainan, 741,
Taiwan, Republic of China (J.A. Deutsch)
CSIRO, Division of Horticultural Research, Box 350, G.P.O. Adelaide, Australia 5001
(W.J.S. Downtown)
Department of Agronomy, University of California, Davis, California 95616, USA ( R. S.
Loomis and W.A. Williams)
Director, Human Nutrition Program, The University of Michigan, M5174 School of
Public Health II, Ann Arbor, Michigan 48104, USA (J. R. K. Robson)
Indigenous Foods Consultants, Inc., 1885 Fuller Road, Ann Arbor, Michigan 48105,
USA (J. Elias)
Institute of Agricultural Research, New Delhi, India
Rodale Press, 222 Main Street, Emmaus, Pennsylvania 18049, USA (A. Cunard)
Stanford University, Stanford, California 94305, USA (J. Frei)
The Close, 15 Cambridge Road, Girton, Cambridge CB3 OPN, England (C.L.A.
Leakey and P. Goode)
University of California, Los Angeles, California 90024, USA (J. Sauer)







UNDEREXPLOITED TROPICAL PLANTS


QUINUA

A staple of the ancient Incas, and still a staple for millions, quinua* is
virtually unknown outside the highlands of Bolivia, Chile, Ecuador, and Peru.
Its grain, rich in protein and containing a good amino acid balance, may prove
to be a better protein source than most of the true cereals.
In the high Andes, quinua is primarily a food of campesinos and poorer
classes; increasing quinua production and use could improve their inadequate
diet. In particular, the greater use of quinua in livestock feeds would result in
better meat production. In highland tropical areas outside of the Andes
quinua could prove valuable for improving nutrition, too.
Although long used for human consumption, quinua seeds have bitter
tasting constituents-chiefly saponins. They are in the seed's outer layer and
can be washed out in cold water. However, this method does not assure the
uniform quality necessary for commercial distribution. Recently, Bolivian
breeders have selected a saponin-free variety, but widespread testing is just
beginning.
Quinua is a hardy plant; before the Spanish Conquest it was one of few
native grains hardy enough for the high Andes. Subsequently, it was largely
supplanted by barley-a less nutritious grain. An annual herb, quinua grows
1-2.5 m tall. It is cultivated at altitudes of 2,500-4,000 m where, with short
day length, the plant matures in 5 or 6 months, producing an abundance of
white or pink seeds in large sorghum-like clusters. These nutritious seeds
contain 58 percent starch, 5 percent sugar, 12-19 percent protein, and 4-5
percent fat.
Quinua seeds are used in soup and ground into flour for bread and cake.
They have also been used to make beer and produce feed for swine and
poultry. A quinua breakfast cereal is manufactured in Peru and quinua has
demonstrated value as a partial wheat-flour substitute for enriching bread.
Quinua leaves are sometimes used as a green vegetable.
Although quinua grows in areas having short day length, cool climates, and
high altitudes, it is possible that new varieties can be created for other
latitudes and altitudes.
Work has been conducted in Peru and Bolivia on the biology of the plant.
Races have been catalogued, variety and fertilizer trials have been conducted
in various localities, and some strains have been selected. The Bolivian
saponin-free variety (cross-bred and selected at the Patacamaya Experiment
Station; see Contacts list page 23) is called sajama. It requires no washing,
has shown no deleterious effects in food or animal feed, and is now being
field tested in the Bolivian and Peruvian Altiplano.

*Chenopodium quinoa Willd. Also known as quinoa. Family: Chenopodiaceae.








CEREALS


Quinua.
(A. Bacigalupo)


Harvesting quinua in Bolivia. (C. B. Heiser)


Two related Chenopodium species are also cultivated as food plants in the
Americas: Cafiihua Chenopodium pallidicaule and Huauzontle Chenopodium
nuttaliae. Cafiihua Chenopodium pallidicaule has an even higher protein
content than quinua and grows at higher elevations in the Andes of Peru and
Bolivia. It is a potential crop plant for extreme highlands in other parts of the







UNDEREXPLOITED TROPICAL PLANTS


world. However, it has low yield, is only a semi-domesticated plant, and will
need much experimental work before it can fulfill its potential.
Huauzontle Chenopodium nuttaliae is cultivated in south central Mexico,
at altitudes of 1,200-3,000 m, largely for its flower clusters (which are used as
a vegetable), although several strains are grown as grains. Protein analyses of
the available varieties should precede attempts to encourage wider cultivation.
This species will hybridize with quinua, which suggests the possibility of
improving both.


LIMITATIONS AND SPECIAL REQUIREMENTS

No intensive research on quinua cultivation has been done: growing methods
have changed imperceptibly during the past four centuries.
Saponins could be a blessing in disguise; their bitterness may deter those
insects and birds that are normally pests in grain fields. Perhaps this is why
strains containing saponins have prevailed.
If not removed, saponins adversely affect the taste and digestibility of
quinua-based animal feeds.
Quinua varieties show highly variable protein content. The Patacamaya
Experiment Station has varieties with 16, 17, 18, and 19 percent protein.


RESEARCH NEEDS

Collection of seeds from all quinua varieties growing throughout the Andean
region is necessary. Safely stored in a seed bank the seeds could provide the
germ plasm needed for genetic improvement, for trials in new locations, and
for implementation of an intensive plant-breeding program.
Initially, all races should be examined to find saponin-free, high-yield
plants with large seeds, high protein content, and good amino-acid balance. A
further requirement is identification of quinua varieties with the highest
nutritive value for domestic animals.
Both intraspecific and interspecific cross-breeding should be attempted. In
addition to the numerous races of cultivated quinua, wild or weedy types are
also recognized (for example, Chenopodium quinoa var. melanospermum).
Some of these weeds may offer useful genes (for example, for disease
resistance). Hybrids between quinua and huauzontle show reduced fertility,
but seed is produced; it should prove possible to transfer genes from one
species to the other.
The effectiveness of saponins as a pest deterrent should be evaluated. It
may be preferable (energetically and ecologically) to mill out the saponins
after harvest rather than to apply pesticides during the growing season.








CEREALS


Selected Readings

Bruin, A. de. 1964. Investigation of the food value of quinua and caiiihua seed. Journal
of Food Science. 29:872-6.
Cardozo, S., J. Rea, and I. A. de Viscarra. 1970. Bibliografia de la Quinua y la Cafihua,
Boletin bibliogrifico # 13. Sociedad de Ingenieros Agr6nomos de Bolivia (La Paz).
Gade, D. W. 1970. Ethnobotany of cafiihua (Chenopodium pallidicaule) rustic seed crop
of the Andes. Economic Botany. 24:55-61.
Gandarillas, H. 1968. Caricteres botinicos mas importantes para la clasificaci6n de la
quinua. In Convenci6n de Quenopodiaceas. Primera, Puno, Perui, Noviembre 5-8.
Anales. Puno, Universidad, Facultad de Agronomia.
Gandarillas, H. 1968. Estudios de Herencia de la Quinoa. Boletin Experimental 35.
Ministerio de Agricultura, Division de Investigaciones, Institute Boliviano de Cultivos
Andinos, La Paz, Bolivia.
Gandarillas, H. 1968. Razas de Quinoa. Boletin Experimental 34. Ministerio de
Agriculture, Division de Investigaciones, Institute Boliviano de Cultivos Andinos, La
Paz, Bolivia.
Le6n, J. 1964. Plantas Alimenticias Andinas. Boletin T6cnico 6, Instituto Inter-
americano de Ciencias Agricolas, Lima, Peri. (Probably the best general reference;
has extensive bibliography.)
Nelson, D. C. 1968. Taxonomy and origins of Chenopodium quinoa and Chenopodium
nuttaliae. Ph.D. Thesis, Indiana University (Available from University Microfilms,
Ann Arbor, Michigan, USA. Order number 69-4792).
Simmonds, N. W. 1965. The grain chenopods of the tropical American highlands.
Economic Botany. 19:223-34.
White, P. L., E. Alvistur, C. Dias, E. Vinas, H. S. White, and C. Collazos. 1955. Nutrient
content and protein quality of quinua and cafihua, edible seed products of the Andes
mountains. Journal of Agricultural Food Chemistry. 3:531-5.
Wilson, H. D. 1974. Experimental hybridization of the cultivated chenopods (Cheno-
podium L.) and wild relatives. Proceedings of the Indiana Academy of Science
(Abstract) 82. Available from author, address below.


Research Contacts and Germ Plasm Supply

Department of Agronomy, Bradfield and Emerson Halls, Cornell University, Ithaca, New
York 14850, USA (H. A. MacDonald)
Department of Plant Sciences, Indiana University, Bloomington, Indiana 47401, USA
(H. D. Wilson)
Direccion de Investigacion Agropecuas, Ministerio de Agricultura, Apartado 2791, Lima,
Peru (A. Bacigalupo)
Direccion General de Desarrollo Agropecuario, Apartado 309, Tegucigalpa, Honduras
(Id. Gandarillas)
FAO, Via delle Terme di Caracalla, 00100, Rome, Italy (J. Leon)
Ministerio de Agricultura, La Paz, Bolivia
Patacamaya Experiment Station, Lavoratorio Experimental de Ciencias Cosmicas,
Universidad Boliviana Mayor de San Andres, 1995 Av. Villazon, La Paz, Bolivia
Program de Cereals, Universidad Nacional Agraria, La Molina, Lima, Peri
Universidad Nacional Agraria La Molina, Apartado 456, Lima, Peri (J. de Albertis and
M. Romero Loli)
Universidad Tecnica del Altiplano, Puno, Perl (M. E. Tapia)







UNDEREXPLOITED TROPICAL PLANTS


ZOSTERA MARINA


Zostera marina* is a marine flowering plant that grows in shallow seawater.
It is one of the few plants that grow and flower fully submerged in seawater.
When ripe, the grain-bearing part breaks loose and floats to the surface where
it drifts to the shore and can then be harvested. Although little is known
about the use of Zostera marina as a grain crop, it yields well in warm, clear,
sun-drenched water. It holds potential as a food crop that can be grown in
tropical estuaries around the world. However, almost nothing is known about
Zostera marina as a crop plant and only exploratory, small-scale research is
warranted at present.
The only recorded case in which the sea has been used for grain
production is that of the Zostera marina harvested by Seri Indians on the
West Coast of Mexico.t The Seri Indians prepared Zostera marina grain by
threshing sun-dried plants with wooden clubs and loosening the fruit by
rolling the seed heads between their palms. The product was winnowed
(tossed in the air), then the grain was toasted, rewinnowed, and ground into
flour. Cooked in water into a thick or thin gruel, the flour has a bland flavor.
Traditionally it was combined with other food, usually sea turtle oil or
honey.
The plant is native to the coasts of the northern hemisphere from the
subarctic to the subtropic. Related species occur in the southern hemisphere.
The grain derived from Zostera marina is 3-3.5 mm long and 1-1.5 mm in
diameter. Like wheat flour, Zostera grain flour is relatively bland and can be
variously flavored. The one sample analyzed to date shows its protein and
starch contents compare favorably with those of wheat, rice, and other
grains: 13.2 percent protein, 50.9 percent starch, and 1.0 percent crude fat.
The leaves of Zostera marina may also prove valuable as fodder, thatching,
or packing material. The foliage is an important food for some sea turtles and
water fowl. An important shallow-water, mud-flat stabilizer, the plant helps
to sustain the productivity of estuarine and other coastal areas.

LIMITATIONS AND SPECIAL REQUIREMENTS

Though transplantation and seeding experiments are under way, and some
previous cultivation work exists, little is known about the propagation or
production of these plants as a crop. Even among the Seri Indians, only the
elderly know about its traditional use within the tribe. Thus, even the
limitations and special requirements of this plant are now unknown.

*Zostera marina. Also known as eelgrass. Family: Potamogetonaceae.
tFelger and Moser, 1973. See Selected Readings.






Zostera marina. (C. P. McRoy)








UNDEREXPLOITED TROPICAL PLANTS


Ted.


The grain from Zostera marina. (C. P. McRoy)


A Seri Indian woman at El Desemboque, Sonora, Mexico, winnowing the grain from
Zostera marina harvested from the sea nearby. (R. S. Felger)


RESEARCH NEEDS

Research on both harvesting procedures and nutritional analysis and use of
Zostera marina seeds is needed. Large-scale collections should be made for
analysis and general experimentation.








CEREALS


Attention should be given to the temperature tolerance and day-length
requirements of varieties from different areas. Attention should also be given
to certain vigorous, wide-leafed varieties, which may produce higher yields.


Selected Readings

Felger, R. S. 1975. Nutritionally significant new crops for arid lands: a model from the
Sonoran desert. In Priorities in Child Nutrition in Developing Countries, ed. Jean
Mayer. Vol. II, Section 16. United Nations Children's Fund, New York. (Order
Number: E/ICEF/L.1328.)
Felger, R. S., and C. P. McRoy. 1975. Seagrasses as potential food plants. In Seedbearing
Halophytes as Food Plants: Proceedings of a Conference, ed. C. Fred Somers.
Del-SG-3-75. pp. 62-9. College of Marine Studies, University of Delaware, Newark,
Delaware, USA.
Felger, R. S., and M. B. Moser. 1973. Eelgrass (Zostera marina L.) in the Gulf of
California: Discovery of its nutritional value by the Seri Indians. Science. 181:355-6.
den Hartog, C. 1970. The Sea Grasses of the World. North-Holland Publishing Company,
Amsterdam.
McRoy, C. P., and R. C. Phillips. 1968. Supplementary bibliography on eelgrass, Zostera
marina. U.S. Fish and Wildlife Service Special Science Report Wildlife 114.
Government Printing Office, Washington, D.C., USA.
Phillips, R. C. 1964. Comprehensive bibliography of Zostera marina. U.S. Fish and
Wildlife Service Special Science Report Wildlife 79. Government Printing Office,
Washington, D.C., USA.


Research Contacts and Germ Plasm Supply
Arizona-Sonora Desert Museum, P.O. Box 5607, Tucson, Arizona 85715, USA (R. S.
Felger)
Department of Botany, Seattle Pacific College, Seattle, Washington 98119, USA (R. C.
Phillips)
Institute of Marine Science, University of Alaska, Fairbanks, Alaska 99701 (C. P.
McRoy)










II ROOTSAND

TUBERS




ARRACACHA

Native to the Andean highlands from Venezuela to Bolivia, arracacha* is an
herbaceous perennial that produces large, thick, edible, carrot-shaped, starchy
roots with a color suggesting parsnip. Arracacha is cultivated today in most
Latin American countries as far north as Costa Rica, usually in small gar-
dens for local use. In the larger cities of Colombia, however, arracacha
roots are sold in considerable quantities. In many areas arracacha replaces the
potato; it costs only half as much to plant and harvest.
If introduced into other high-altitude areas of the tropics, arracacha is
likely to be a valuable root crop, particularly if improved cultivars and
cultural techniques are developed. The tubers are reported to have a starch
content ranging from about 10 to 25 percent and to be rich in calcium and
phosphorus. The starch is similar in many respects to that of cassava; it is
easily digested and can be used in infant and invalid foods. It also makes a
suitable laundry starch.
Secondary tubers (offshoots of the main tuber) are an important
carbohydrate foodstuff and are boiled or fried as a table vegetable or used as
an ingredient in stews. They have a delicate flavor, a crisp texture, and,
depending on the cultivar, white, creamy-yellow, or purple flesh. In many
areas yellow tubers are preferred.
All other parts of the plant are also used: offsets for the next planting, the
coarse main rootstocks and mature leaves for livestock feeding, young stems
for salads or a table vegetable.
Arracacha thrives in any good soil and is cultivated like, and often
interplanted with, potatoes. The secondary tubers usually mature 10-14
months after planting; sometimes an early harvest of immature roots is taken
after about 4-8 months. The entire plants are pulled up with the roots
attached.
Seeds are seldom produced; propagation is entirely vegetative. Planting can
be done at any time, but is usually done at the beginning of the rainy season.
*Arracacia xanthorrhiza Bancroft. Family: Umbelliferae. Also known as Peruvian carrot,
arracha, Peruvian parsnip, and Arracacia esculenta DC.








UNDEREXPLOITED TROPICAL PLANTS


A Colombian farmer among rows of arracacha, a crop for highland regions. (F. Higuitia
Mufioz)


". .
FrY -.




(;,if


Arracacha: The roots are ready for market. (F. Higuitia Mufioz)







ROOTS AND TUBERS


In Colombia, arracacha is sold in sacks, 60 kg each. (F. Higuitia Mufioz)

LIMITATIONS AND SPECIAL REQUIREMENTS

Except in the lowlands, arracacha yields at all elevations in the Andes. It
requires a moderate, evenly distributed rainfall of at least 60 cm (but
preferably 100 cm); if the natural rainfall is insufficient, supplementary
irrigation is required. For optimum results an equable temperature of
15-200C throughout the year is needed. There are some varieties-those
normally grown at lower elevations-that are frost sensitive, but the varieties
adapted to the higher altitudes, where they do get occasional and light frosts,
appear not to be seriously harmed by them.
In some regions arracacha is susceptible to nematode attack, but this can
be controlled successfully with a copper-based pesticide.
Harvesting cannot be delayed because roots left in the ground become
fibrous and tough and develop a strong, unpleasant flavor. Because of a short
shelf life, it can be a relatively high-priced product in the marketplace.







UNDEREXPLOITED TROPICAL PLANTS


RESEARCH NEEDS

Arracacha cultivation should be tested in the highlands and hill country of
East Africa, Central Africa, India, Southeast Asia, New Guinea, etc. Some
remnants of old introductions may still exist in the highlands of Central
America (e.g., Guatemala) and the West Indies (Jamaica, Cuba, and Puerto
Rico); local agronomists should investigate. Given some research attention the
remnants may provide material for arracacha improvement and expansion.
Little direct testing of the environmental tolerances of arracacha has been
conducted; study of the latitude, altitude, temperature, soil type, and
moisture requirements is needed. A study of pathogens infecting arracacha
should also be made.
Three varieties of cultivated arracacha (distinguished mainly by the color
of the flesh of the roots) are known. Wild varieties may exist in the Andean
region; they should be sought and preserved. No analysis of the relative
nutritional and agronomic merits of even the existing varieties has been done.
Research on this is needed.



Selected Readings

Constance, L. 1959. The South American species of Arracacia (Umbelliferae) and some
related genera. Torrey Botanical Club Bulletin. 76:39-52.
Hodge, W. H. 1954. The edible Arracacha-a little known root crop of the Andes.
Economic Botany. 8(3):195-221.
Higuitia Mufi6z, F. 1968. El cultivo de la arracacha en la sabana de Bogoti. Agriculture
Tropical. 24(3):13946.
Higuitia Mufi6z, F. 1969. Comparative yield of nine varieties ofArracacia xanthorrhiza.
Agriculture Tropical. 25(9):566-70. Field Crop Abstracts. 24(1):1015.
Le6n, J. 1967. Andean tuber and root crops: origins and variability. Proceedings First
International Symposium. Tropical Root Crops, 1 Pt. 1:121.
Kay, D. E. 1973. TPI Crop and Product Digest No. 2: Root Crops. Tropical Products
Institute, London. (Available from Publications Section, Tropical Products Institute,
56/62 Gray's Inn Road, London WC1X 8LU, England. Price 1.50 plus postage.)



Research Contacts and Germ Plasm Supply
Botanical Museum, Harvard University, Oxford Street, Cambridge, Massachusetts 02138,
USA (R. E. Schultes)
Department of Botany, Indiana University, Bloomington, Indiana 61701, USA (C.
Heiser)
Institute de Ciencias Naturales de la Universidad Nacional, Apartado 2535, Bogota,
Colombia (A. Fernindez-P6rez)
L. H. Bailey Hortorium, Cornell University, Ithaca, New York 14850, USA (W. Hodge)







ROOTS AND TUBERS


COCOYAMS


Great effort has been devoted to introducing and adapting the potato to the
lowland tropics, while indigenous tropical root crops have been largely
neglected. Cocoyams,* native to the Americas, are already adapted to tropical
conditions and have been successfully introduced to other tropical regions,
especially West Africa. There are about 3040 cocoyam species growing
randomly throughout the tropics, but only five or six are important sources
of edible products. Despite their adaptability, acceptance, and commercial
food value, cocoyams have received little attention by researchers. Con-
sequently, their potential is not being realized, and their use is declining.
Much of the potential of cocoyams lies in commercial (rather than
subsistence) production. If agronomists select high-yield, good-quality culti-
vars, and develop a technology for their intensive cultivation, cocoyams could
become a major tropical food crop. Their future depends particularly on
reducing production costs, possibly by mechanizing some of the cultural
practices.
Cocoyams have a central tuberous root (corm) surrounded by smaller
potato-sized tubers (cormels). Only the cormels are normally used for human
consumption. The corms are used for animal feed and for replanting. Capable
of yielding 30-60 tons of cormels per ha, cocoyams can be grown in various
types of soil. Like potatoes, the cormels may be boiled, baked, parboiled,
fried in oil, or ground into flour. In West Africa, fresh tubers are ground (to
produce fufu) and used to thicken stews and soups.
The cormels compare with potatoes in nutritive value. They contain 2-3
percent protein (fresh weight) but are deficient in lysine, methionine and
cysteine. Rich in minerals and vitamins, they are palatable energy foods. The
tender leaves and shoots are a nutritious, spinach-like vegetable.
Some cocoyam varieties yield a cormel crop in as little as 3 months, others
in 10 months. Cormels can be harvested individually as each matures, or they
can be left until all mature and then harvested simultaneously. Some cultivars
(in fairly dry soil) can be left in place for as long as 2 years without the
cormels deteriorating. Harvested cormels can be stored in a cool, dry place for
2-3 months with little effect on quality.
Cocoyams grow best at low to medium altitudes in the humid (frost-free)
tropics. Riverine land, too wet for sweet potatoes and yams, is well suited for
cocoyams. Some varieties, however, also grow well in dry soils. For optimum
yields they require deep, well-drained, rich soil and 140-200 mm of rain, well


*Xanthosoma sagittifolium, Xanthosoma violaceum, Xanthosoma brasiliense, Xantho-
somaatrovirens. Also known as tania, tanier, yautia, new cocoyam, etc. Family: Araceae.







UNDEREXPLOITED TROPICAL PLANTS


distributed throughout the year. In areas where the rainfall is inadequate they
can be grown under irrigation.
Cocoyams can be grown within a wide temperature range, but do best in
an average annual temperature of about 240C. They are relatively disease- and
pest-free. The most common diseases are soft-rot and root-rot. Care must be
taken to avoid bruising the tubers during harvest; otherwise they are liable to
rot in storage.


LIMITATIONS AND SPECIAL REQUIREMENTS

Because virus diseases can devastate root crops, extreme caution should be
exercised and quarantine enforced when cocoyams are introduced to new
areas.
Cocoyams require abundant and well-distributed rainfall. Where prolonged
droughts occur they are not likely to flourish unless irrigated.
Like most root crops, cocoyams have specific soil requirements.


Cocoyam roots and the edible corms that surround them. Individual corms can be
harvested (as shown here by the stump visible in the center of the roots) leaving the
plant in the ground for the others to mature. (D. L. Plucknett)







ROOTS AND TUBERS


Cocoyams approaching maturity in a small rural farm in Nigeria. (D. L. Plucknett)


Cocoyam corms in a village market in Ghana. Cocoyam is suited to small-farmer
production in rural areas. (E. S. Ayensu)

In commercial ventures, where cocoyams are grown under mass culti-
vation, pest and disease problems can be expected to increase in severity.


RESEARCH NEEDS

Many cocoyam varieties exist and they differ widely in yield, adaptation to
soils and climate, plant characteristics, corm size, palatability, and starch
content. Such varieties must be collected from many tropical regions and
their food potential determined.







UNDEREXPLOITED TROPICAL PLANTS


Superior varieties should be field tested together (under quarantine) to
determine performance and cormel quality. With the genetic variability
available, and the simplicity of clonal selection, varieties with increased yield
and quality and higher protein levels must be selected.
Many (or most) cocoyam plants are infected by virus. Although not fatal
to the plant, the infection does reduce yield. The virus is found in the corms
and cormels, so planting them transmits the virus. But reproducing cocoyams
by seed-generally thought to be impossible but recently shown by
researchers at the University of Florida (see address below) to be eminently
feasible-produces new plants that are virus free. The modern technique of
tissue culture also promises to remove the infection. Once virus-free
cocoyams are obtained, a certification program and strict quarantine will be
needed to avoid reinfection.
Other agronomic factors requiring research are spacing, fertilizer, soil and
water requirements, pest and weed control, and a complete study of the
physiology of tuber formation.
Nutritional research is also needed because nothing is known about the
biological value of cocoyam protein or the digestibility of the starch.
Research is needed to industrialize cocoyam products. The feasibility of
producing fried cocoyam chips and flour on a commercial scale should be
investigated.



Selected Readings
Abrufia-Rodrigues, F., E. G. Boneta-Garcia, and J. Vicente-Chandler. 1967. Experiments
on tanier production with conservation in Puerto Rico's mountain region. Journal of
Agriculture, University of Puerto Rico. 51(2):167-75. (Available from The Agri-
culture Experiment Station, Rio Piedras, Puerto Rico.)
Coursey, D. G. 1968. The edible aroids. World Crops. 20(4):25-30.
Coursey, D. G., and P. H. Haynes. 1970. Root crops and their potential as food in the
tropics. World Crops. 22(4):261.
de Albuquerque, M., and E. Pinheiro. 1970. Buerosas Feculantas. Serie: Fitotecnia.
1(3):33-47. Institute de Pesquisas e Experimentacao Agropecuarias do Norte. (Now:
Centro de Recuros Naturais de Amaz6nia, Belem, Pari, Brazil.)
Irvine, F. D. 1969. Xanthosoma. In West African Agriculture 3rd Ed. Vol. 2: West
African Crops. pp. 177-9. Oxford University Press, London.
Karikari, S. K. 1971. Cocoyam cultivation in Ghana. World Crops. 23(3):118-22.
Kay, D. E. 1973. TPI Crop and Product Digest No. 2: Root Crops. Tropical Product
Institute, London. (Available from: Publications Section, Tropical Products Institute,
56/62 Gray's Inn Road, London WC1X 8LU, England. Price 1.50 plus postage.)
Morton, J. F. 1972. Cocoyams (Xanthosoma caracu, X. atrovirens, and X. nigrens),
ancient root and leaf vegetables gaining in economic importance. Proceedings of
Florida State Horticulture Society 85:85-94.
Praquin, J. Y., and H. C. Miche. 1971. Essai de conservation de taros et macabos au
Cameroun. Institute Recherche Agronomique Tropicales Rapport prelim No. 1.
Dschang Station, Cameroon.







ROOTS AND TUBERS


Winters, H. F., and G. W. Miskimen. 1967. Vegetable Gardening in the Caribbean Area.
Agriculture Handbook No. 323. pp. 77-79. U.S. Department of Agriculture,
Agriculture Research Service, Washington, D.C., USA.

Research Contacts and Germ Plasm Supply
Agriculture Research and Education Center, University of Florida, 18905 SW. 280 St.,
Homestead, Florida 33030, USA (R. B. Volin)
Agricultural Experiment Station, Rio Piedras, Puerto Rico (J. Vicente-Chandler)
Department of Plant Pathology, University of Florida, Gainesville, Florida 32611, USA
(F. W. Zettler).
Mayagiez Institute of Tropical Agriculture, Mayagiiez, Puerto Rico 00708 (F. Martin).
University of the West Indies, St. Augustine, Trinidad (J. A. Spence).







TARO


The taro* is widely grown; its tuberous roots are rich in starch and, like
potatoes, can be boiled, baked, roasted, or fried in oil. However, only in
Egypt, the Philippines, Hawaii, and certain other Pacific and Caribbean
islands is the taro a commercial crop. With increased research and
commercialization in the rest of the tropics, taro, with its exceptional yields
and year-round production, could help overcome food shortages. It has
particular potential for marshy, waterlogged regions and for coastal and
salinified regions (because some cultivars are highly salt tolerant).
Underground, taro usually has one central corm and 6-20 spherical cormels
around it. Both corm and cormels are eaten. They are often used as rice
substitutes in Pacific and Asian countries. From the flesh, which is usually
mealy and has a delicate, nutty flavor, a flour similar to potato flour can be
produced for soups, biscuits, bread, beverages, and puddings. Easily digested,
taro starch can be used in baby foods, hypoallergenic foods, and as a cereal
substitute in diets for victims of celiac disease. In Hawaii, taro is made into
poi-a paste made from boiled, mashed corms fermented a day or so. It is also
sliced and fried into taro chips.
Low in protein and fat, taro is essentially a carbohydrate food.
Nutritionally it compares favorably with other root crops-cassava, yams,


*Colocasia esculenta (L.) Schott (sometimes called Colocasia antiquorum.) Also known
as old cocoyam, dasheen, malanga, tania, tanier, tanyah, elephant ear. Family: Araceae.







UNDEREXPLOITED TROPICAL PLANTS


Taro corm surrounded by the edible tubers. The variety shown here is the dasheen.
(U. S. Department of Agriculture)


Irish potato, sweet potato-and with cereal crops, especially rice. It is a good
source of minerals: calcium, phosphorus, and vitamins A and B. Taro leaves
and petioles can be cooked and eaten like spinach. They provide protein,
calcium, phosphorus, iron, potassium, and vitamins A, B, and C.
Taros are adapted to flooded environments and, like rice, can be grown in
paddy culture. Under paddy they are grown in all soil types. They grow
rapidly if fertility and water levels are maintained; the corms mature 6-18
months after planting.








ROOTS AND TUBERS


Taro garden, western Samoa. Here the crop is being grown under dry-land conditions.
(D. L Plucknett)


In marshy areas such as this in Hawaii, taro is grown like rice under flooded paddy
conditions. (D. L. Plucknett)







UNDEREXPLOITED TROPICAL PLANTS


Taro can also be grown in dry, upland areas if water is provided by
irrigation or by rainfall (mulching may be needed to maintain high soil
moisture). Grown "dry" the best results are obtained on deep, well-drained,
friable (particularly alluvial) loams.
The plant responds well to intensive agriculture: land preparation,
planting, and harvesting can take place during all seasons. A field may often
have taro plants in various stages of maturity, and the grower can also sell
them year-round as they mature.
After harvest the tubers can be stored for up to 3 months, depending on
variety.
In Hawaii taros have a high and profitable yield. In the island of Kauai,
2.14 million kg of corms have been produced from only 69 ha. In 1969, the
prices paid for raw corms ranged from 17 to 20 cents/kg. From an average
yield of 22,400 kg/ha the gross income per ha was almost $4,000.*
Several taro types, characterized by numerous, symmetrical, smaller tubers
called dasheens, are grown in dry-land agriculture. Although popular in China,
Japan, and among Asians throughout the tropics, dasheens are largely
neglected plants. With high yields, high nutritive value, and superior keeping
quality, they have great unrealized potential. Grown either rain fed or
irrigated, dasheens mature more rapidly than paddy-grown taro-and yield
less. They grow best in loose, water-retentive, clay soils. Usually planted at
the beginning of the rainy season, they can, if carefully managed, be
produced year-round. Dasheen shoots are highly prized by the Japanese and,
if canned, they offer tropical countries a good export potential.


LIMITATIONS AND SPECIAL REQUIREMENTS

Transporting taro root germ plasm throughout the world is dangerous. It can
spread phytopathogens, which severely decrease yield, to new areas. For
example, the virus diseases and the taro leaf hopper, Tarophagus proserpina
Kirkaldy, that transmits them, occur in New Britain and the British Solomon
Islands. Importing germ plasm from those islands must be avoided at all costs.
Taro growing requires intensive effort. It calls for manual labor and long
hours of work in muddy, flooded fields; consequently its production is
decreasing.
With all the variation available it is essential to select the appropriate
variety for the specific location. For optimum results taros require hot,
humid conditions, with daily average temperatures of 21-270C. In more
temperate areas, or at high altitudes, there must be a 6-7 month frost-free
period.
*Plucknett and de la Pefia. 1971. See Selected Readings.







ROOTS AND TUBERS


Water control is absolutely necessary. Upland taros and dasheens require
well-distributed, year-round rainfall (or substitute irrigation) and a long
growing season.
If stored, corms must be kept dry and injury free. Dasheens can be stored
at 100C for up to 6 months. In Egypt taros are stored at 7C for more than 3
months at a time. Solomon Islands taro corms cannot be stored; decay begins
within a week of harvest.


RESEARCH NEEDS

Phytopathogens such as dasheen mosaic virus are widespread among taro.
Removing the pathogens will give an immediate increase in yield. Repro-
ducing taro by planting corms and cormels also transmits the infection, but
two avenues promise to produce virus-free plants-tissue culture and
reproduction via seeds. Taro tissue culture has been successfully accomplished
in Hawaii and offers hope for clearing cultivars of viruses. Though taro will
flower and set seed, there has never been a breeding program either for
removing pathogens or for genetic improvement. Once pathogen-free taro is


Peeling taro, western
Samoa. (D. L.
Plucknett)







UNDEREXPLOITED TROPICAL PLANTS


obtained, a certification program and strict quarantine will be required to
maintain it.
In Hawaii, taro and dasheen varieties are well known, and production
techniques well developed. The U.S. organizations that fund technical
assistance should support efforts to distribute varieties and disseminate
information about taros and dasheens throughout the tropics.
Taro production must be modernized: mechanization, crop management
systems, and weed control are the most critical needs. Mechanization in the
paddy environment offers engineers a great challenge. Mechanical methods
for planting taro are badly needed. Planting on ridges is a possibility (it also
simplifies water control and harvesting). Mechanical harvesting is even more
challenging. Ultimately it may prove necessary to drain and dry the fields
before mechanical harvest. Adapting small, hand-propelled rice cultivators has
brought some progress in mechanization to Hawaii.* Upland taro mechaniza-
tion is in its early stages, but it can be done (on a plantation scale) using
modified tomato transplanters and potato diggers.
Research on virus diseases of taro is critical. The virulent virus in New
Britain and the Solomon Islands is under study (at Malaita; see Research
Contacts), but increased support and effort is essential to prevent its spread
to new areas.
The pathogens responsible for decay of stored corms have been identified;
research is needed on the use of fungicides and other methods to combat
them.
The development of processed taro food products that could be used in
hypoallergenic specialty foods would stimulate interest in the crop.
Basic botanic and agronomic knowledge of dasheens is inadequate. Much
more research is warranted. Collection and evaluation of dasheen varieties
would be an important first step. Cultivars must be collected and conserved
to prevent their loss.


Selected Readings
Barrau, J. 1953. Taro (an annotated bibliography). South Pacific Commission Quarterly
Bulletin. 3(4):31-2.
Gooding, M. J., and J. S. Campbell. 1961. The improvement of cultivation methods in
dasheen and eddoe (Colocasia esculenta) growing in Trinidad. Proceedings of the
American Horticultural Society, Caribbean Region. 5:6-20.
Greenwell, A. B. H. 1947. Taro-with special reference to its culture and use in Hawaii.
Economic Botany. 1(3):276-89.
Hodge, W. H. 1954. The Dasheen, a Tropical Root Crop for the South. U.S. Department
of Agriculture Circular No. 950. U.S. Department of Agriculture, Washington, D.C.,
USA.


*Plucknett et al. 1970. See Selected Readings.








ROOTS AND TUBERS


Jackson, G. V. H., and D. E. Gollifer. 1975. Disease and Pest Problems of Taro
(Colocasia esculenta L. Schott) in the British Solomon Islands. PANS. 21(1):45-53.
Kay, D. E. 1973. TPI Crop and Product Digest No. 2: Root Crops. Tropical Products
Institute, London. (Available from: Publications Section, Tropical Products Institute,
56/62 Gray's Inn Road, London WC1X 8LU, England. Price 1.50 plus postage.)
Miller, C. D. 1927. Food Values of Poi, Taro, and Limu. Hawaii Agricultural Experiment
Station Bulletin 78. University of Hawaii, Honolulu, Hawaii.
Plucknett, D. L., R. S. de la Pefia, and R. Obrero. 1970. Taro (Colocasia esculenta). Field
Crops Abstracts. 23(4):413-26.
Plucknett, D. L., and R. S. de la Pefia. 1971. Taro production in Hawaii. World Crops.
23(5):244-9.
Plucknett, D. L., H. C. Ezuman, and R. S. de la Pefia. Mechanization of taro culture
in Hawaii. Proceedings, 3rd International Symposium on Tropical Root and
Tuber Crops, Nigeria. (In Press)
Tisbe, V. 0., and T. G. Cadiz. 1967. Corm and root crops: taro or gabi. In: Vegetable
Production in Southeast Asia. Eds., J. E. Knot and J. R. Deanon, Jr. pp. 293-300.
Los Banos University of the Philippines, College of Agriculture, Laguna, Philippines.
Whitney, L. D., F. I. A. Bowers, and M. Takahashi. 1939. Taro Varieties in Hawaii.
Hawaii Agricultural Experiment Station Bulletin 84. University of Hawaii, Honolulu,
Hawaii.


Research Contacts and Germ Plasm Supply
Agricultural Research and Education Center, University of Florida, 18905 SW 280 St.,
Homestead, Florida 33030, USA (R. B. Volin)
Dala Research Station, Malaita, British Solomon Islands (G. V. H. Jackson and D.
Gollifer)
Department of Agriculture, Suva, Fiji (P. Sivan)
Department of Agronomy and Soil Science, College of Tropical Agriculture, University
of Hawaii, Honolulu, Hawaii 96822, USA (D. L. Plucknett)
Department of Plant Pathology, University of Florida, Gainesville, Florida 32611, USA
(F. W. Zettler)
International Institute of Tropical Agriculture, P.M.B. 5320, Ibadan, Nigeria (H. S.
Ezumah)
Kauai Branch Station, Kapaa, Kauai, Hawaii 96746, USA (R. S. de la Pefia)
Lyon Arboretum, University of Hawaii, Honolulu, Hawaii 96822, USA
Mayagiiez Institute of Tropical Agriculture, Mayagiiez, Puerto Rico 00708 (F. Martin)
Plant Pathology Department, Rothamsted Experimental Station, Harpenden, Herts,
England AL5 2JQ (A. J. Kabek)
South Pacific Regional College of Tropical Agriculture, Apia, Western Samoa (W. Cable)










III VEGETABLES







CHAYA

Chaya,* a fast-growing ornamental and shade shrub, is a source of nutritious
green leaves and shoots. It requires little maintenance (for example, the soil
around it does not need tilling) and produces large amounts of greenery for
years. A few plants grown experimentally in Puerto Rico have outgrown and
outproduced all other leafy vegetables.
The attractive shrubs, 3-5 m tall, are often seen as hedges in Mexico and
Honduras. Native chaya grows in thickets or open forest (often in rocky
places) at altitudes up to 1,300 m. There are two forms: Cnidoscolus
aconitifolius is found in native dooryards from southern Mexico to Costa
Rica; Cnidoscolus chayamansa is grown as a hedge or dooryard plant in the
Yucatan peninsula of Mexico and in British Honduras. Cnidoscolus chay-
amansa is occasionally grown in Florida and Cuba, but seems not to have
been disseminated to other regions.
Chaya's young shoots and tender leaves are cooked and eaten like spinach.
Reportedly they are high in protein, calcium, iron, carotene, thiamine,
riboflavin, niacin, and ascorbic acid. They are probably suitable for canning
or freezing for local and export markets, but this has not yet been attempted.
So far, chaya appears free of the pests and diseases that plague green
garden vegetables in tropical climates, an important economic and ecological
advantage. However, horn worms can rapidly defoliate it (but the plants
quickly recover their leaves).
Chaya is propagated from stem cuttings, and woody stem sections
germinate readily. Edible greenery is produced within 2 or 3 months. Because
of the softness of the wood, the plant is easily pruned and maintained within
reach of the ground. The plants tolerate heavy rainfall and respond with
luxurious growth. Drought is also tolerated, and plants recover well when the
rain returns.


*Cnidoscolus chayamansa McVaugh and Cnidoscolus aconitifolius. Also known as tree
spinach. Family: Euphorbiaceae.







UNDEREXPLOITED TROPICAL PLANTS


Freshly plucked chaya leaves. Before being eaten they are boiled in water and become
tender, but chewy. (J. Morton)


LIMITATIONS AND SPECIAL REQUIREMENTS

The horticulture of chaya has never been studied.
The plants vary from smooth to hairy, and the hairy plants sting like
nettles, so that harvesters must wear gloves. The stinging disappears with
cooking. Cultivated plants are almost free of stinging hairs; it is likely that
this is the result of long years of selection by the harvesters.
Chaya must be cooked before eating: the fresh leaves contain toxic
hydrocyanic glycosides, but cooking inactivates them.







VEGETABLES


Chaya grows prodigiously and can reach a height of more than six feet. This single plant
is just three years old. (F. Martin)


RESEARCH NEEDS

Experimental plantings of cuttings of Cnidoscolus chayamansa (the less hairy
of the two species) should be established, and those plants selected that have
a minimum of hairs and contain a minimum of hydrocyanic glycosides.
Bioassays should be undertaken to verify the apparent wholesomeness of
this vegetable-special attention should be paid to the toxins.
Trial plantings should be made to determine yield per hectare, labor
requirements, and other factors bearing on the feasibility of commercial
production.
Investigations should be made into the potential for processing and
marketing the product-fresh, canned, or quick-frozen.
Cuttings should be distributed for testing in tropical areas outside its
native home.








UNDEREXPLOITED TROPICAL PLANTS


Selected Readings
Berlin, B., D. E. Breedlove, and P. H. Raven. 1974. Principles of Tzeltat Plant
Classification. Academic Press, New York and London.
McVaugh, R. 1944. The genus Cnidoscolus: generic limits and intrageneric groups.
Bulletin Torrey Botanical Club. 71(5):457-74.
Munsell, H. E. et al. 1949. Composition of food plants of Central America. I-Honduras.
Food Research. 14(2):144-64.
Souza-Novelo, N. 1950. Plantas Alimenticias y Plantas de Condimento que Viven en
Yucatin. Institute T6cnico Agricola Henequenero, M6rida, Mexico, pp. 101-4.
Standley, P. C., and J. A. Steyermark. 1949. Flora of Guatemala. Fieldiana Botany.
24(6):59-60. Field Museum of Natural History, Chicago, Illinois, USA.

Research Contacts and Germ Plasm Supply
Colegio de Postgraduados, Escuela Nacional de Agricultura, Chapingo Texcoco, Mexico
(E. Hernandez X)
Fairchild Tropical Garden, 10901 Old Cutler Road, Coral Gables, Florida 33156, USA
(J. Popenoe)
Mayagiiez Institute of Tropical Agriculture, Mayagiiez, Puerto Rico 00708
Oficina de Asesoria T6cnica, Edificio "Centroamericana," 7A, Avenida 7-78, Zona 4,
Oficina 605, Guatemala, Guatemala, Central America (J. Colina Campollo)







HEARTS OF PALM


There is an increasing market throughout the world for expensive, exotic,
foods; an example is the growing demand for palm hearts.* A tropical
delicacy, palm hearts are the growing tips of palm trees. Reminiscent of
artichoke hearts, they may be added to salads, served as a vegetable, or used
to enhance the flavor of other vegetables. Although the demand for palm
hearts is larger than the supply, little awareness of their commercial potential
exists outside Brazil and Costa Rica.
World consumption increases daily. Brazil's abundance of wild palms has
long been utilized, but rising demand is threatening their extinction: to
obtain the heart, the tree must be killed.
Cultivation of palm trees for palm hearts is long overdue. Cultivation
offers a practical way to circumvent forest destruction and to preserve
existing stands. Rising labor costs and the increasing difficulty of harvesting


*Also known as palm cabbage and palmitos.

































Many palms can be used as a source of hearts of palm. This is Euterpe edulis, which, in
Brazil, is widely harvested for this purpose. The "heart" is inside the smooth portion of
the stem, visible here between the fruit clusters and the leaves. (W. H. Hodge)


the thinning wild stands provide economic incentives for plantation culture.
In Brazil, replanting is already mandatory, and cultivation is being
encouraged.
The palm heart is a cylindrical bundle of leaf bases. The heart may be
several inches in diameter and several feet long. Its composition and food
value is similar to that of cabbage (Brassica).
The possibilities of establishing palm hearts as a plantation crop are good.
Fast growing palms, well suited for this purpose, are recognized, and other
potential species are abundant. A few, such as pejibaye (Guilielma gasipaes;
see page 73), produce several stems emerging from a common root cluster, so
that only one stem, not a whole plant, is sacrificed to harvest the heart.
In the past, palm hearts have been harvested entirely from wild specimens
of Euterpe, Prestoea, Guilielma, Roystonea, Sabal, Acrocomia, and other
palms in tropical America and the West Indies. Brazil is the principal supplier
of canned palm hearts for the North American market. Brazilian assai
palms (Euterpe edulis Mart.), both wild and cultivated, have been a source of
palm hearts since the mid-1960s. In the past few years in Costa Rica, pejibaye








UNDEREXPLOITED TROPICAL PLANTS


The heart of a palm. (R. W. Read)


palm has been set out in plantations for the production of palm hearts. When
the seedlings are 3' years old, the hearts are harvested and canned. It is
reported that other potential commercial palms are Sabal spp., Euterpe
oleracea Mart., Caryota spp., and the coconut palm Cocos nucifera L.







VEGETABLES


Canned hearts of palm are widely exported. (W. H. Hodge)


Euterpe and pejibaye are common in humid tropical forests of South
America. Euterpe also grows in the West Indies, while coconut thrives on
tropical coasts and neighboring inland regions of the northern and southern
hemispheres. Caryota spp. are common in forests at low and medium eleva-
tions in the Philippines and throughout Southeast Asia. Other genera known
for the wholesomeness and palatability of their hearts are Astrocaryum,
Genonoma, Hyospathe, Iriartea, Prestoes, Socrates, and Welfia.


LIMITATIONS AND SPECIAL REQUIREMENTS

Not all species of palms have edible hearts. Some are bitter or tough, and
some may actually be toxic (for example, the heart of Orania species). Some
hearts are very difficult to remove. Coconut palms are subject to serious








UNDEREXPLOITED TROPICAL PLANTS


diseases (such as lethal yellowing), and it is not known what effect such
diseases would have on the quality of the terminal bud at the time of harvest.



RESEARCH NEEDS

The first requirement is to collect as many promising species as possible in
order to select palms appropriate for use as a palm heart plantation crop.
Trial plantings should be made to determine if any can surpass the current
commercial palm heart sources.
Studies of the botanical, agronomic, and economic aspects of palms as raw
material for palm hearts are essential. Surveys should be made of existing
palm heart plantations to note the present procedures and possibilities for
improvement. Research is needed to clarify the details of productivity, labor
requirements, and economic return to grower and processor.


Selected Readings
Camacho, E., and J. Soria V. 1970. Palmito de pejibaye. Proceedings Tropical Regional
American Society of Horticulture Science. 14:122-32.
Hodge, W. H. 1965. Palm cabbage. Principes. 9(4):124-31.


Research Contacts and Germ Plasm Sources
Bailey Hortorium, Cornell University, Ithaca, New York 14853, USA (H. E. Moore)
Biological Station, Las Cruces, Costa Rica (R. G. Wilson)
Botanic Gardens, Calcutta, India
Centro de Pesquisas Florestiis, Faculdade de Florestas, Caixa postal 2959, Curitiba,
Parand, Brazil
Centro de Recursos Naturais da Amaz6nia, Beldm, Pari, Brazil
Department of Botany, Smithsonian Institution, Washington, D.C. 20560, USA (R. W.
Reed)
Fundaqao Centro de Desenvolvimento Industrial CEDIN, Rua Alvares Cabral 16, 40 and.,
Salvador, Bahia, Brazil.
Fundaqao Coopercotia, Cooperativa Agricola de Cotia, Cotia, Sao Paulo, Brazil
Institute Imteramericano de Ciencias Agricolas, Turrialba, Costa Rica
Jardin Botinico, Apartado ABreo 1 5660, Secretaria de Desarrollo y Fomento,
Department del Valle del Cavea, Rep6blica de Colombia (V. M. Patiflo)
Jardim Botinico, Rio de Janeiro, Brazil (Pe. R. Reitz)
Laboratoire d'Ethnobotanique, Jardin des Plantes, Paris, France (J. Barrau)
Leao, Marilene, and M. Cardoso. 1974. Instrucoes para a Cultura do Palmiteiro
(Euterpe edulis). Superintendencia do Desenvolvimento do Litoral Paulista, Instituto
Agronomico de Campinas, Sao Paulo. Brazil.
Royal Botanic Garden, Peradeniya, Sri Lanka
Summit Gardens, Panama, Panama







VEGETABLES


WAX GOURD


Grown throughout the Asian tropics, the wax gourd* is little known
elsewhere. Its melon-like fruit has a thick flesh that is white, crisp, and juicy.
An outstanding feature is its resistance to spoilage. Preserved from attack of
microorganisms by its waxy coating, the fruit can be stored without
refrigeration for as long as a year. The plants are prolific, rapid growers (over
a 4-day period one shoot grew an average of 2.3 cm every 3 hourst. Three
or four crops can be produced each year. The wax gourd is now grown mainly
as a household crop, but the market could be greatly expanded. It has
important potential as a new vegetable for large areas of Latin America and
Africa.
The fruit can be consumed during various stages of maturity. The
mild-flavored, easily digested flesh may be used as a cucumber substitute, a
cooked vegetable, or food extender. The Chinese use it in soup. In India and
Cuba, a popular sweet is made by cooking the pulp in syrup.
The fruit contains 96 percent water, 0.4 percent protein, 0.1 percent fat,
3.2 percent carbohydrate, and 0.3 percent mineral matter. There are two
distinct types: round and elongated. Hairy when young, they grow to
immense proportions. They may measure as much as 2 m long and 1 m in
diameter, and weigh up to 35 kg. The thin, tough skin is coated with white,
chalky wax. (Some varieties have minute hairs even when mature.) The pulp
has many flat, oval, light-brown seeds up to 2.5 cm long, which can be fried
and eaten (like pumpkin seeds). They also yield a pale yellow oil, which has
not been studied.
Young leaves, flower buds, and vine tips are boiled and eaten as greens.
The plant, an annual, creeping vine, resembles a pumpkin vine. It is
reportedly easier to grow than any other cucurbit (pumpkin, squash, melon,
etc.). Usually planted on mounds or ridges, the fruit is harvested in less than 5
months; in Sri Lanka, seeds sown in the rainy season produce wax gourds in 2
months. The plants can be grown on a trellis, but since the heavy, succulent
fruit needs strong supports, the plants are sometimes grown over roofs and
trees. In China the seed is planted on the banks of village ponds, and the
plants grow over a bamboo framework erected over water. This method
provides abundant water for the plant, and the framework over the water
permits the land to be used for other purposes.

*Benincasa hispida (Thumb.) Cogn. (B. cerifera Savi.). Also known as white gourd,
ash-gourd, and petha. Family: Cucurbitaceae.
tHerklots, G. A. C. 1972. See Selected Readings.




































Wax gourd. (J. Morton)


Wax gourd. (J. Morton)







VEGETABLES


The wax gourd is relatively drought tolerant. In India, the furrows are
flooded at weekly intervals during the dry season, but not during the rainy
season unless there has been no precipitation for 10 or 12 days.
The seeds remain viable for 10 years and germinate in 1 or 2 weeks. Pest
and disease problems are minimal. Young fruit is protected by its hairy cover,
maturing fruit by its waxy coat.


LIMITATIONS AND SPECIAL REQUIREMENTS

The wax gourd is an ideal food for those with excess weight or digestive
problems. Its only handicap is its mild taste. Those accustomed to richer fare
may not like it without the addition of seasonings or other vegetables or
fruits of strong flavor. It is similar in flavor and texture to the chayote
(Sechium edule).
Wax gourds grow best in medium-dry lowlands. They do not grow well in
high-rainfall areas.


RESEARCH NEEDS

Minimal research is needed to extend the use of wax gourds. The primary
need is to acquaint farmers and consumers with its possibilities.
Food technology studies to develop its market potential could help its
introduction to new areas.
Commercial seed sources are needed.

Selected Readings
Agnibotri, B. N. 1948. Petha-its cultivation and economic uses. I & II Indian Food
Packer. 2(2):9-10; and 2(12):17-18.
Herklots, G. A. C. 1972. Vegetables in South-East Asia. Hafner Press, Macmillan
Publishing Co., Inc., New York.
Morton, J. F. 1971. The wax gourd-a year-round Florida vegetable with unusual
keeping quality. Proceedings of Florida State Horticulture Society. 84:104-9.
Srivastava, V. K., and S. C. P. Sachan. 1969. Grow ash-gourd the efficient way. Indian
Horticulture. 14(1):13-5.

Research Contacts and Germ Plasm Supply
Department of Horticulture, Chia-yi Agriculture Experiment Station, Chia-yi, Taiwan,
China (Chu Ching-Kuo, Head)
Hawaii Agricultural Experiment Station, Honolulu, Hawaii 96822, USA (S. Nakahara)
Tropi-Pak, 3664 N.W. 48th St., Miami, Florida 33142, USA (D. Murasaki)
E. R. Witt, 1037 Brock St., Corpus Christi, Texas 78412, USA







UNDEREXPLOITED TROPICAL PLANTS


WINGED BEAN


The winged bean*t is a tropical legume with a multitude of exceptionally
large nitrogen-fixing nodules. It produces seeds, pods, and leaves (all edible by
humans or livestock) with unusually high protein levels; tuberous roots with
exceptional amounts of protein; and an edible seed oil.
The winged bean has important potential for small-scale farmers. It is a
fast-growing perennial that is particularly valuable because it grows in the wet
tropics where protein deficiency in human diets is not only great but difficult
to remedy. Winged bean seeds rival soybeans in oil and protein content, and
the plant has the added advantages of protein-rich roots and edible foliage.
Though relatively unknown, this multipurpose legume appears to meet
many dietary needs of the tropics. It is grown in quantity only in Papua New
Guinea and Southeast Asia.
A twining vine, it grows to over 3 m when supported. The pods have four
longitudinal jagged "wings" and they contain up to 20 seeds, each weighing
about 3 gm. The smooth, shiny seeds may be white, brown, black or mottled.
The roots are numerous: they grow horizontally at shallow depth and become
thick and tuberous about 2 months after planting. Excellent nodulation
without need for inoculation has occurred wherever the crop is grown, even
on sites cleared from virgin forest. Individual winged bean plants may carry
over 600 nodules, and the fresh weight of the large nodules can reach 0.85
tons/ha.
Neither pests nor disease appear to be a serious threat. Nor do soil
requirements appear to be demanding. Winged bean crops have always been
grown in regions having fairly heavy rainfall. The lower limit has not been
established. The plant thrives in regions with an annual rainfall of 250 cm or
more.
The winged bean is cultivated largely for its young, tender pods, which are
sliced and cooked, much like green beans. Pods are picked beginning 10
weeks after sowing, and the plant continues to bear pods indefinitely. The
young leaves and shoots may also be eaten as a leafy vegetable.
Unripe seeds can be used in soups. Ripe seeds are roasted and eaten like
peanuts. The nutritive value of the ripe, dry seeds is very close to that of


*Psophocarpus tetragonolobus (L.) DC. Also known as four-angled bean, Goa bean,
asparagus pea. Family: Leguminosae.
tThe exceptional promise of this plant is detailed in a companion publication, The
Winged Bean: A High Protein Crop for the Tropics, available without charge. To order
see page 188.
tMasefield. 1961. See Selected Readings.








VEGETABLES


In Papua New Guinea winged beans are grown on stakes for pods and seeds (back-
ground) and grown unstaked for tubers and as a ground cover (foreground). The
plant grows vigorously, forming dense masses of vegetation. Prostrate plants seldom
flower, but staked plants flower and bear copious fruit. (N. D. Vietmeyer)

soybeans (34 percent protein and 18 percent oil*). The protein is high in
lysine-8 percent of the total amino-acid content (without tryptophan). More
than 60 percent of the fatty acids in the oil are unsaturated. The seeds are
rich in tocopherol, an antioxidant that increases vitamin A use in the human
body (vitamin A deficiency is common in many tropical regions).
The winged bean may have high yield potential. Yields of about 2.5 tons of
seed/ha have been reported.t If this is confirmed as a fair average the winged
bean will be among the top-yielding tropical grain legumes.
The immature tuberous roots are eaten like potatoes. They are reported to
contain over 20 percent protein (dry weight basis). An edible tropical root
crop with such high protein content could be of immense help in reducing
protein malnutrition, particularly since winged beans grow well in the regions
where inhabitants already live on low protein root crops such as cassava.
Perhaps after harvesting the crop for pods, seeds, or roots, the haulm can
be fed to animals. It is reportedly palatable to livestock.$ Like all other parts
of the winged bean, the foliage has a remarkably high protein content.


LIMITATIONS AND SPECIAL REQUIREMENTS

Winged bean varieties now cultivated for pods and seeds must be grown on
stakes. This-and the fact that all pods do not ripen simultaneously-restricts

*Pospisil et al 1971. See Selected Reading..
tlbid.
lIbid.









UNDEREXPLOITED TROPICAL PLANTS


Small charcoal-blackened winged bean tubers cooked in hot ashes by highland tribesmen
in Papua New Guinea. The tubers contain ten or twenty times the protein of other root
crops. (N. D. Vietmeyer)







VEGETABLES


their use to the small (or village) farmer. The winged bean cannot yet be
considered for mass commercial planting.
Because of antinutrition factors, mature winged bean seeds must first be
cooked before they can be used for human consumption.* This phenomenon
is common to several other leguminous seeds, including soybeans. Immature
seeds can be eaten raw without ill effects.
The climatic requirements of the winged bean have not been studied in
depth.


RESEARCH NEEDS

A detailed analysis of winged bean research needs appears in the companion
report: The Winged Bean: A High-Protein Crop for the Tropics. (See page
187.
Because seed sources are scarce, the varietal composition is virtually
unknown. It will be necessary to collect several varieties, especially in
Southeast Asia; to propagate them; and to run comparative trials (with seed
from various sources) in the wet tropics of Africa, Latin America, and Asia.
The chief obstacle to the further investigation of the crop is the difficulty
in obtaining seed. There is little available because there has never been a need
for it in quantity. Seed supplies must be increased before large-scale
experiments can be undertaken. The best seed available must be used; a
random selection may lead to unjustifiably poor results.
Variations in pod length and number of seeds per pod should be
considered when seeking high-yielding varieties. There may also be genetic
variation in root yield, or in foliage yield and composition. Only comparative
trials can provide definitive answers.
The phenology of different varieties should be studied for use in breeding
programs aimed at producing high-yielding types with uniform time of
flowering and seed maturation.
Research is needed to find agronomic practices, climatic conditions, and
soil conditions that give optimum yields.
The relative yield of pods and seeds from supported and unsupported
plants should be explored. It would be useful to investigate the possibility of
harvesting first a seed crop and then a root crop, maintaining reasonable
yields for both.
The winged bean's ability to enhance soil fertility for subsequent crops is
worth detailed examination. It would also be beneficial to determine its use
as a forage.


*Crevost and Lemari6. 1921. See Selected Readings.








UNDEREXPLOITED TROPICAL PLANTS


Possible toxicants and antinutrition factors in the mature seeds need
analysis and detailed study. Research should also include an amino acid assay
and an investigation into the overall nutritional value of the roots.
Other major research needs include:
Determining digestibility of protein at different stages of development
of leaves, stems, pods, etc.;
Investigating seed physiology and the germination and storage of seeds;
Developing ways to prepare the dry beans and roots; and
Studying the plant's palatability and value for livestock.


Selected Readings
Burkhill, I. H. 1935. Dictionary of the Economic Products of the Malay Peninsula. Vol.
2. Greenwood Press, Inc., Westport, Connecticut, USA.
Cr6vost, C., and C. Lemari6. 1921. Catalogue des products de 1'Indochine. Bulletin
Economique de l'Indochine. 23:121.
Masefield, G. B. 1967. The intensive production of grain legumes in the tropics. Soil and
Crop Science Society of Florida Proceedings. 27:338.
Masefield, G. B. 1961. Root nodulation and agricultural potential of the leguminous
genus Psophocarpus. Tropical Agriculture, Trinidad. 38:225.
Masefield, G. B. 1973. Psophocarpus tetragonolobus-a crop with a future? Field Crop
Abstracts. 26(4):157-160.


Winged beans are commonly seen in vegetable markets in Thailand. They are widely used
in soups, chow mein, and other traditional dishes. (N. D. Vietmeyer)








VEGETABLES 61


National Academy of Sciences. 1975. The Winged Bean: A High-Protein Crop for the
Tropics. Washington, D.C., USA.
Pospisil, F., S. K. Karikari, and E. Boamah-Mensah. 1971. Investigations of winged bean
in Ghana. World Crops. 23:260-4.
Purseglove, J. W. 1968. Tropical Crops: Dicotyledons. Vol. 1. John Wiley, New York.


Research Contacts and Germ Plasm Supply
Agricultural Research Station, University of Ghana, Kade, Ghana (S. K. Karakari).
Department of Agriculture, University of Papua and New Guinea, P. O. University,
Papua New Guinea (T. N. Khan).
Department of Agricultural Science, University of Oxford, United Kingdom (G. B.
Masefield)
Department of Agronomy, University of Illinois, Urbana, Illinois 61801, USA (T.
Hymowitz).
International Institute of Tropical Agriculture, P.M.B. 5320, Ibadan, Nigeria (K. O.
Rachie).
A more complete list of research contacts can be found in the National Academy of
Sciences' report noted above.










IV FRUITS






DURIAN


Although the durian* is grown only in Malaysia, Indonesia, southern
Thailand, and the Philippines, it is one of the best known and most
controversial of all fruits. Though there are many places in the West Indies,
tropical America, Africa, and Oceania where it should grow well, the durian is
important only to Southeast Asia. It has received no research attention and
today our knowledge of durian is virtually the same as when, in the 15th
century, it was first observed by Europeans.
Though Malays and other people in the Far East are very partial to it, the
fruit has met with a mixed reception from Europeans. Many are repelled by
its strong, disagreeable odor, but others quickly become extremely fond of it.
The taste, difficult to describe, is sweet, aromatic, and persistent. The odor
has been referred to as "a mixture of old cheese and onions flavored with
turpentine" or as "custard passed through a sewer." But durian enthusiasts
are not bothered by the odor: the 19th-century British naturalist, Alfred
Russel Wallace, considered that "it was worth a journey to the East, if only to
taste of its fruit."t
The huge fruit vary from spherical to oval and may grow as large as 30 cm
long and 15 cm in diameter and weigh up to 20 kg each. Their hard, thick
skins are covered with sharp prickles. The interior is divided into five cells,
each containing up to four seeds enveloped in a firm, cream-colored pulp.
Nutritionally, the fruit is an important source of carbohydrate, fat, and
vitamins, and contains some protein.
Durian can be prepared in various ways. The ripe pulp is commonly eaten
fresh, or it can be preserved for use in ice cream, candy, or other sweets. The


*Durio zibethinus Murr. and related species. Family: Bombacaceae.
tHe also described it as "a rich butter-like custard highly flavoured with almonds, but
intermingled with it come wafts of flavour that call to mind cream-cheese, onion
sauce, brown-sherry, and other incongruities. Then there is a rich glutinous smoothness
in the pulp which nothing else possesses, but which adds to its delicacy. It is neither
acid nor sweet, nor juicy, yet one feels the want of none of these qualities for it
is perfect as it is."







FRUITS


pulp of unripe fruit may be used as a vegetable. When cooked the seed is also
edible.
Wild animals, particularly elephants, tigers, and monkeys, are very
attracted to the fruit. Harvesters build shelters beneath wild durian trees so
they can get to the fruit before the animals.
There are at least five species of durian, but only one is well known. The
others, all potentially important species, are virtually unknown, even in
Malaysia. Several have edible fruits said to taste as good as (or better than)
the common durian. The species are:
Durio zibethinus Murrs. (the common durian) Distribution: widespread
throughout Southeast Asia. Haphazardly cultivated or semiwild.
Durio kutejensis Becc. Distribution: Borneo (Kalimantan, Sarawak, and
Sabah). Slightly cultivated, but mainly wild.
Durio oxleyanus Griff. Distribution: South Sumatra and Borneo. Little
known even locally; exclusively a wild plant.
Durio graveolens Becc. Distribution: East Borneo. Rare wild and even
rarer cultivated.
Durio dulcis Becc. Distribution: Borneo. Only in the wild.
Odor varies greatly among the five species. Some have only a slight odor;
Durio graveolens produces odorless fruit. One variety of Durio kutejensis has
a mild, inoffensive odor.
Durio kutejensis may offer better fruit quality than the common durian
because its flexible soft spines make it easier to handle.
All five species are medium-sized or large trees, 20-40 m tall. Usually
propagated from seeds, they grow vigorously. They are planted in humid
lowland areas below 800 m elevation. Improved varieties can be easily
reproduced by budding them onto 1-year-old rootstocks of the same species.
Durian trees are productive and, even with little care, provide important
revenue for villagers and farmers.



LIMITATIONS AND SPECIAL REQUIREMENTS

As mentioned, the strong odor is offensive to many people. It is attributed to
indole derivatives.
There has been little attempt to organize durian marketing, quality
control, harvesting, etc.
The trees are slow to produce and only begin bearing after 7 years. Each
fruit takes 3 months to develop and is not fully 'ripe until it drops from the
tree. Falling fruit is a hazard for gatherers.


Durian fruits. (E. S. Ayensu)







UNDEREXPLOITED TROPICAL PLANTS


The custard-like pulp must be eaten shortly after harvest because it
quickly turns rancid and sour. Since fruit is not easily transported, only local
distribution of fresh fruit can be considered at present.
The seeds quickly lose their viability, which makes it difficult to introduce
the species to other regions. A few durian trees have been introduced to
Honduras, however, and the fruits are much sought after (apparently the odor
was not an insurmountable obstacle).
Since durian trees in Southeast Asia neither receive nor require much
attention nothing is known about the best methods for pruning, irrigation,
pest control, etc.
The tree does not thrive where there is a distinct dry season.


RESEARCH NEEDS

Durian horticulture, breeding, and selection are needed. Durians have many
varieties that offer great possibilities for improvement, but detailed analysis is
still lacking. Agronomic research is needed to select elite strains from each
species, improve horticultural practices, and introduce durians to new tropical
regions.
Food technology research is needed, particularly for preserving, trans-
porting, and processing the fruit or flesh.

Selected Readings

Ochse, J. J. et al. 1961. Tropical and Subtropical Agriculture. The Macmillan Company,
Collier-Macmillan Ltd., London.
Popenoe, W. 1920.'Manual of Tropical and Subtropical Fruits. The Macmillan Company,
New York.
Soegeng Reksodihardjo, W. 1962. The species of Durio with edible fruits. Economic
Botany. 16(4):270-82.
Stanton, W. R. 1966. The chemical composition of some tropical food plants: VI.
Durian. Tropical Science. 8(1):6-10.
Valmayor, R. V., R. E. Coronel, and D. A. Ramirez. 1965. Studies on floral biology,
fruit set and fruit development in durian. Philippines Agriculture. 48(8-9):355-66.
Wyatt-Smith, J. 1953. Materials for a revision of Malayan Durio with notes on Bornean
species. Kew Bulletin. 4:513-34.


Research Contacts and Germ Plasm Supply
Herbarium Bogoriense, Bogor, Indonesia. (A. Kostermans)
W. Soegeng Reksodihardjo, Pioneer Hi-Bred International Inc., Des Moines, Iowa 50309,
USA.
University Herbarium, School of Biological Sciences, University of Malaya, Kuala
Lumpur, Malaysia (B. C. Stone)







FRUITS


MANGOSTEEN


Often described as one of the world's best-flavored fruit, the mangosteen* is
highly esteemed in Southeast Asia. In other tropical areas this fruit is known
only in botanical gardens and small experimental orchards. Curiously, it is
unavailable in what could be its major markets: Central America, South
America, Australia, and Africa, where it would be readily accepted if it could
be economically produced. It also has great potential for export to North
America, Europe, and the Middle East.
Mangosteen culture has been attempted in many humid, lowland tropical
areas. However, because of horticultural difficulties no widespread com-
mercial production has been successful-even in the Far East where the fruit,
which commands high prices, is picked from uncultivated, wild trees.
Extending its use offers a formidable research challenge.
The mangosteen grows in high rainfall areas-over 2,500 mm per
year-where, because of the high humidity, few commercial crops can be
economically cultivated.
The fruit-the size of a tennis ball-contains a segmented, white (almost
translucent) pulp that is protected by a purple shell 6 mm thick. The pulp is
sweet, subacid, and agreeably flavored. Of all the exotic tropical fruits the
mangosteen is perhaps the one most readily accepted by western palates.
The tree is a slow-growing evergreen with large, dark green leaves. It thrives
best in warm, humid, rainy climates with few seasonal variations in rainfall
and temperature. But mangosteen trees have been grown successfully under
dry conditions with irrigation. Temperatures between 200 and 300C are ideal,
especially if they are not subject to sudden changes-cool spells (4C) can be
fatal to young trees. The trees rarely grow over 10 m in height.
Deep, fertile, well-drained, slightly acid soils are needed to grow the best
trees and to produce the heaviest yields. Under such conditions, yields of
200-800 fruits per tree have been obtained in good years. They are harvested
at maturity and must be handled carefully to prevent damage. The tough,
thick rinds should enable the fruit to be shipped and marketed. If
refrigerated, the fruit can be stored for several weeks.

LIMITATIONS AND SPECIAL REQUIREMENTS

Though the mangosteen has long been regarded as having great potential if its
horticultural limitations could be eliminated, it has received very little
research attention from trained horticulturists. Consequently, today there are


*Garcinia mangostana L. Family: Guttiferae.






UNDEREXPLOITED TROPICAL PLANTS


Mangosteen fruit. (U. S. Department of Agriculture)


no improved varieties that sustain high production and that have good
commercial characteristics. The horticultural limitations are due to the
following factors:
Mangosteen seeds reproduce the characters only of the mother plant;
there is no genetic variation produced. This makes the production of superior
types difficult.
Growers hesitate to plant mangosteen orchards because of the delay
before their investment brings return: seedlings take as long as 15 years to
produce a profitable crop.
No reliable method has been found for propagating the plants
vegetatively.
It is difficult to establish the plant in environments other than those
identical to its natural habitat.
Mangosteen plants tend to bear only in alternate years.


RESEARCH NEEDS
To stimulate mangosteen production and make it commercially viable,
considerable research should be directed toward solving its basic horticultural
problems.
Research is needed to discover ways of shortening the time the plants take
to mature. There is particular need to develop better vegetative propagation







FRUITS


methods (for example, to find rootstocks suitable for grafting). Mangosteen
appears to be graft-compatable with other species of Garcinia.

Selected Readings
Hume, E. P. 1950. Difficulties in mangosteen culture. Malayan Agriculture Journal.
33(2):104-7.
Krishnamurthi, S., and V. N. Madhava Rao. 1965. The mangosteen, its introduction and
establishment in peninsular India. In Advances in Agricultural Science. pp. 401-20.
Agricultural College and Research Institute, Coimbatore, India.
Ochse, J. J. et al. 1961. Tropical and Subtropical Agriculture. The Macmillan Company,
Collier-Macmillan Ltd., London, England.
Popenoe, W. 1920. Manual of Tropical and Subtropical Fruits. The Macmillan Company,
New York.
Pynaert, E. 1954. Le mangoustanier. Tract no 37. Publication de la Direction de
1'Agriculture des Foret et de 1'Elevage, Brussels, Belgium.

Research Contacts and Germ Plasm

Agricultural College and Research Institute, Coimbatore, India (S. Krishnamurthi)
Botanic Gardens, Kebun Raya, Bogor, Indonesia (S. Idris)
Department of Agriculture, Bangkok, Thailand (Pairoj Pholprasit)







NARANJILLA


Naranjilla,* "the golden fruit of the Andes," has great potential for the
future, though at present it is little known outside its native home, Colombia
and Ecuador. An excellent dessert fruit, it is also used to flavor confections,
jelly, jam, and other preserves.
Freshly squeezed naranjilla juice is used in Ecuador and Colombia to make
sorbete, a green, foamy drink with an appealing sweet-sour flavor of
pineapple and strawberry. In Panama, Guatemala, and Costa Rica, where the
plant has been introduced, the fresh juice is processed into frozen
concentrate.
The plant is a large, robust shrub (1-2 m high) with hairy leaves and
spherical yellow-orange fruit, sometimes as large as tennis balls, densely
covered with easily removed white hairs. The acidulous, yellow-green pulp has
numerous seeds. Unaffected by season, fruit is produced throughout the year.
*Solanum quitoense Lam. Also known as lulo. Family: Solanaceae.








UNDEREXPLOITED TROPICAL PLANTS


The shrubby naranjilla bush under cultivation in Ecuador. (C. B. Heiser)


Naranjilla fruit. (W. H. Hodge)







FRUITS


In Ecuador, the naranjilla grows best on fertile, well-drained slopes of
humid, upland valleys where the annual rainfall is at least 1,500 mm. The
plant grows rapidly and bears large quantities of fruit. It yields 1,000 to
2,000 kg of fruit per ha with little care.


LIMITATIONS AND SPECIAL REQUIREMENTS

The plants have exacting climatic requirements. Frost sensitive, they need
good drainage and moderately cool and rather humid climate at altitudes of
800-2,000 m. The plant does not thrive in the lowlands.
They are susceptible to rootknot nematodes, viruses, fungal disease, and
parasites, which shorten life and reduce production, particularly in sandy
soils. Therefore, in Ecuador, new land-uncontaminated by these pests-is
used for each planting. Seedlings or grafted plants begin to bear when they
are 6-12 months old and continue to produce fruit for about 2 years before
they begin to lose vigor (because of the pests) and must be replaced.
The naranjilla plant is easily controllable in Colombia and Ecuador.
However, it is a well-established weed in some localities of Costa Rica.
The plants need frequent fertilization (preferably once a month) and water
during dry periods.


Solanum quitoense in the public market, Pasto, Colombia. (R. E. Schultes)







UNDEREXPLOITED TROPICAL PLANTS


RESEARCH NEEDS

Little improvement of naranjilla has been attempted. Research emphasis
should be on finding varieties and rootstocks resistant to nematodes and the
fungal and bacterial diseases that limit production. The closely related
Solanum hirtum crosses with naranjilla, is tolerant of rootknot nematodes,
and is a promising species for breeding and rootstock. Another nematode-
resistant relative is Solanum macranthum. It may make good rootstock.
Widening naranjilla's adaptation to climate and soil type would increase its
use throughout the tropics. Research is therefore recommended. Investigators
should test Solanum topiro, crossed or grafted with naranjilla, because it
grows at lower elevations and yields a larger (also popular) fruit.

Selected Readings
Garcia-Reyes, F. 1967. El cultivo de lulo en la zona cafeteria colombiana. Revista
Cafetera. 17(142):75-7.
Gattoni, L. A. 1961. La naranjilla. Ministerio de Agricultura, Panama.
Heiser, C. B., Jr. 1969. Nightshades, the Paradoxical Plants. W. H. Freeman and Co.,
San Francisco.
Hodge, W. H. 1947. El lulo, una fruta andina poco conocida. Revista Facultad Nacional
de Agronomia, Medellim, Colombia 7:147.
Hodge, W. H. 1947. Naranjillas, or "little oranges" of the Andean Highlands. Journal
New York Botanical Gardens. 48(571):155-60.
Ledin, R. B. 1952. The naranjilla (Solanum quitoense Lam.). Proceedings of Florida
State Horticulture Society. 65:187-90.
Munier, R. 1962. La culture du lulo en Colombia. Fruits. 17(2):91-3.
Pacheco, R., and J. Jimenez. 1968. El cultivo de la naranjilla en el Ecuador. Ministerio de
Agriculture y Ganaderia, Quito, Ecuador.
Patiflo, V. M. 1963. Plantas cultivadas y animals domesticos en America equinoccial. V.
1. Printing Department, Call, Colombia. p. 403.
Schultes, R. E., and J. Cuatrecasas. 1953. Notes on the cultivated lulo. Harvard
University Botanical Museum Leaflets. 16:97.
Schultes, R. E. and R. Romero-Castafieda. 1962. Edible fruits of Solanum in Colombia.
Harvard University Botanical Museum Leaflets. 19:235-286.
Romero-Castafieda, R. 1961. El lulo: una fruta de importancia econ6mica. Agriculture
Tropical. 17(4):214-18.



Research Contacts and Germ Plasm Supply
Agriculture Attach6, American Embassy, San Jose, Costa Rica (A. G. Krevorkian)
CATIE, Inter American Institute of Agricultural Sciences, Turrialba, Costa Rica (J. Soria
V.)
Indiana University, Bloomington, Indiana 61701, USA (C. B. Heiser)
Jardfn Botinico, Universidad del Valle, Cali, Colombia (V. M. Patifio)
Jefe Seccion de Botinica, Instituto de Ciencias Naturales, Apartado 7495, Bogoti,
Colombia







FRUITS


PEJIBAYE


Other than the coconut, date, and African oil palm, few plants of the family
Palmae have been widely exploited. Many could become useful sources of
oil and food. A notable example is pejibaye, or peach palm.* It could become
an important commercial crop throughout the humid tropics. Probably the
most balanced of all tropical foods, its fruit contains carbohydrates, protein,
oil, minerals, and vitamins.
Although favorably mentioned by Spanish writers centuries ago, pejibaye
today is little known outside Central America and northern South America. It
is a palm with many spiny trunks emerging from a common root stock. The
fruit, 2-6 cm long, is borne in bunches weighing up to 12.5 kg and consisting
of up to 300 fruits. There may be as much as 13 bunches on a single trunk
and, under ideal conditions, two crops are harvested per year. The fruit is a
starchy mesocarp surrounding a seed. It is not sweet; its flavor and texture are
reminiscent of chestnuts. Pejibaye fruit has twice the protein content of
banana and can provide more carbohydrate and protein per hectare than
maize.
Pejibaye fruit is usually prepared by boiling in salted water. The skin is
removed before eating. To preserve the fruit, it is boiled and then dried. It
can be restored to original consistency and flavor-even after 6 months or
more-by a second brief boiling. It is also delicious when roasted.
In addition to the fleshy mesocarp, the white, hard-shelled seed kernel is
sometimes eaten. It tastes somewhat like coconut and has a high percentage
of oil.
Planted in tropical America since ancient times, sizable pejibaye stands
now exist in Costa Rica, and innumerable dooryard trees are scattered over
the lowlands of Brazil, Costa Rica, Panama, Colombia, Peru, Venezuela, and
Ecuador. The pejibaye is of major economic importance throughout the
region. At least part of the year it supplies the principal food for many
inhabitants.
The plant is adapted to tropical conditions, preferring regions where
annual rainfall is 2,500 mm or less. In Costa Rica it grows at all elevations
from sea level to 1,200 m, and occasionally as high as 1,500 m. It grows best
in heavy soil: clay loam, or clay.


*Guilielma gasipaes (H.B.K.) L. H. Bailey. Formerly known as Guilielma speciosa Mart.
and Guilielma utilis Oerst. Also known as Bactris gasipaes H.B.K. and Guilielma chon-
taduro Triana. Commonly called pejibay (Central America) also spelled pejivalle, etc.,
piriguao (Venezuela), pijuajo (Peru), paripou (French Guiana), and pupunha (Brazil).
Family: Palmae







UNDEREXPLOITED TROPICAL PLANTS


Pejibaye fruits. (P. H. Alien, courtesy W. H. Hodge)


Commonly, propagation is by seeds, although the plants form suckers
readily (an important benefit for commercial plantings for it allows superior
varieties to be replicated easily). When grown from seed, the pejibaye begins
to bear after 6 or 8 years and has an economic life of 75 years or more. Once
established, the plant requires little care.
Varieties of the pejibaye are not well defined, but there are many. Varietal
differences in fruit size, fruit-cluster size, spine length, and fruit color are
known.
Because of its multiple stems pejibaye is one of the most promising palms
for the plantation production of hearts of palm (see page 49).




























.I9





















ppk
'I





P jb e (W'.H,,
e j W Hodge)
Pejibaye. (W. H. Hodge)







UNDEREXPLOITED TROPICAL PLANTS


LIMITATIONS AND SPECIAL REQUIREMENTS

The major barrier to propagating large numbers of pejibaye for commercial
plantations is the lack of superior cultivars. There is a scarcity of elite stock
material (suckers). Seedlings vary too much in quality and performance-and
take too long to bear-to warrant large investment. Existing selections are not
sufficiently productive, despite claims to the contrary. Seedless (partheno-
carpic) types are lower in quality and color and are not so productive as
seeded types.
The trunks of most pejibaye strains are densely covered with spines, but
the northwest Amazon has spineless races. Harvesting is difficult and expen-
sive. Cutting off too many of the spines kills the palm.


RESEARCH NEEDS

Collection of seed, classification of cultivars, diffusion of seed, and
information on the pejibaye crop could lead to its cultivation in many areas.
An intensive campaign is necessary to expand its cultivation, beginning with
the areas in which it is already familiar.
Efforts must be concentrated on management and varietal selection
(especially to select spineless varieties). There are some little-known varieties,
mostly found in the northwest Amazon region, that lack spines. These should
be collected and selected for use in propagation and crossbreeding.
Food technologists should test ways to can and preserve pejibaye because
at present the fruit is not easy to store or transport in quantity. So far, most
food research has concentrated on its nutritive value,
Agronomists should study the value of interplanting other crops among
the pejibaye for this could provide a cash return while the pejibaye are
maturing.
The pejibaye research at Centro Agron6mico Tropical de Investigaci6n y
Ensefianza in Turrialba, Costa Rica, should receive full support from technical
assistance agencies. Funds should also be allocated for a campaign to extend
their results to other tropical countries.

Selected Readings
Johannessen, C. L. 1966. Pejibaye palm: yields, prices and labor costs. Economic
Botany. 20(3):302-15.
Johannessen, C. L. 1966. Pejibayes in commercial production. Turrialba. 16(2):181-7.
(Available from the author, address below.)
Johannessen, C. L. 1967. Pejibaye palm: physical and chemical analysis of the fruit.
Economic Botany. 21(4):371-8.
Patifio, V. M. 1958. El cachipay o pijibay, en la cultural de los indigenas de la America







FRUITS


intertropical. Institute Indigenista Interamericano. Mexico. Ediciones Especiales.
39:176-203, 293-331.
Popenoe, W. and O. Jim6nez. 1921. The pejibaye, a neglected food plant of tropical
America. Journal of Heredity. 12(4):151-66.
Seibert, R. J. 1950. The importance of palms to Latin America; pejibaye a notable
example. Ceiba. 1(2):65-74.

Research Contacts and Germ Plasm Supply
Centro Agr6nomico Tropical de Investigaci6n y Ensefianza, Turrialba, Costa Rica (E.
Camacho)
Centro Regional de Investigaciones Agropecuarias del Noroeste, Ministerio de Agri-
cultura, Tarapoto, Per6 (M. Slaveria)
Department of Geography, University of Oregon, Eugene, Oregon 97403, USA (C. L.
Johannessen)
Institute de Investigaciones Agro Industriales, Lima, Perui (C. Florez Cossio)








PUMMELO


To produce fruit of high quality and maximum yield most citrus crops (i.e.,
oranges, lemons, tangerines, tangelos) require subtropical climates with cool
winters and warm summers. The pummelo,* however, is a citrus fruit ideally
suited to the vast lowland tropical zone; the uniformly warm climate reduces
the quality and yield of other citrus, but the pummelo appears to thrive.
The pummelo is native to Southeast Asia where it has been cultivated for
centuries. In Thailand, where it is most highly cultivated, fine commercial
varieties-with a shelf life as long as 4 months-have been exported to
neighboring countries for more than 60 years.
An attribute of the pummelo is its relatively high tolerance to saline
conditions. This tolerance has been exploited in Thailand; unproductive
coastal lowlands around river deltas and brackish marshy areas are devoted to
pummelo cultivation. The popular belief in Thailand is that the flavor and
quality of the fruit are enhanced by the salt. However, this is questionable
and requires experimental proof.
Pummelo is a crop with potential for coastal lowlands elsewhere in the

*Citrus grandis (L.) Osbeck. Also known as shaddock, toronja, pamplemousse, etc.
Family: Rutaceae.



































Pummelo. (K. and J. Morton)


Pummelo tree, Florida. (J. Morton)







FRUITS


tropics, especially those where climate, moisture, and salinity prevent
cultivation of other popular citrus fruits.
Although the pummelo has been introduced into citrus-growing areas of
the world, the varieties chosen produced disappointing fruit, inferior in
quality to the best in Southeast Asia.
Pummelo trees are generally medium sized, 5-15 m tall when mature. They
have broad, shiny leaves; the young branches are covered with spines. The
fruit is green or yellow and is the largest among the citrus varieties, larger
even than grapefruit. They are either spherical or pear shaped, and have a
thick (up to 2 cm) rind. The internal segments are formed of firm juice sacs
vesicless). The best varieties have a pleasant balance of acid and sugar and
leave no bitter aftertaste.


LIMITATIONS AND SPECIAL REQUIREMENTS

For optimum performance, pummelos require warm, frost-free climates with
well-drained soils and adequate moisture.
There are few research or agricultural extension reports on pummelos.
Citrus canker is a common affliction of pummelo trees in Southeast Asia.


RESEARCH NEEDS

Considerable information on pummelos has been accumulated by generations
of growers in Southeast Asia. It needs to be collated and evaluated by
experienced horticulturists. But more data are needed if pummelo cultivation
is to be adapted successfully outside Southeast Asia. We must know about
varietal behavior, such as the best rootstocks for different soils, the
unpredictable seedlessness of some types, and the tolerance and susceptibility
to diseases.
Research to select superior varieties is helped by the genetic characteristics
of pummelo: the seeds of most citrus tend to reproduce the characters
of the mother plant, but pummelo seeds are gametic (they contain only one
embryo, which is subject to genetic segregation) and give rise to plants with
entirely new horticultural characters. This produces a wealth of varieties to
choose from.
Testing of rootstocks and cultivars in different kinds of soils is also
needed, especially in coastal, saline-soil locations.
Using superior varieties collected in Southeast Asia, scientists should
establish test plots in new tropical locales in Africa, Latin America, Oceania,
and Australia.







UNDEREXPLOITED TROPICAL PLANTS


Selected Readings
Fairchild, D. 1927. The pink fleshed pummelo of Java. Journal of Heredity.
18(10):425-7.
Groff, G. W. 1927. Culture and varieties of the Siamese pummelo as related to
introductions into other countries. Linnean Society Journal. 5(3):187-254.
Ochse, J. J., M. H. Soule, Jr., M. J. Dijkman, and C. Wehlburg. 1961. Tropical and
Subtropical Agriculture, Vol. 1. Collier-Macmillan, Ltd., London.
Reuther, W., et al. 1967. The Citrus Industry. Vol. 1. University of California at
Riverside, Riverside, California.
Soost, R. K. 1964. Self-incompatibility in Citrus grandis (L.). Proceedings of the
American Horticulture Society. 84:137-40.

Research Contacts and Germ Plasm Supply
Agricultural Research and Educational Center, University of Florida, 18905 S.W. 280th
Street, Homestead, Florida 33030, USA (S. Malo)
Department of Agriculture, Bangkok, Thailand (Pairoj Pholprasit)
University of California at Riverside, Riverside, California 92502, USA (R. K. Soost)







SOURSOP


The soursop* is a tropical fruit with potential for development as a processed
industrial commodity. Native to and common in tropical America and the
West Indies, it was one of the first fruits carried from the New World to other
tropical regions. It has become popular in areas as diverse as southern China,
Australia, and Africa. Though mainly eaten as a fresh fruit, soursop can be
processed and preserved without losing its aromatic flavor. Because of its
distinctive qualities and its desirability for puree, nectar, ice cream, and jelly,
it offers developing countries excellent export possibilities. European and
North American markets appear particularly promising.
The soursop tree flowers and bears fruit more or less continuously, though
there usually is a principal ripening season. Varying in form and size, the fruit
often weighs 4 kg or more. The white, fibrous, juicy flesh smells somewhat
like pineapple, but the musky, rather acid flavor is unique. Soursops are
usually cut in sections and the flesh eaten with a spoon. The pulp is often
added to fruit cups or salads, or chilled and served as dessert, but generally it

*Annona muricata L. Also known as guanibana (in Spanish) and graviola (in Brazil).
Family: Annonaceae.







FRUITS


is used in ice cream or is mixed with water and sugar to make a refreshing
drink. Frozen pulp is sold in plastic bags in Philippine supermarkets; fresh
juice is marketed in waxed, cardboard cartons in the Netherlands Antilles.
The soursop fruit has many black seeds scattered through the pulp, but
most of its closely packed segments are seedless. The fruit contains 12
percent sugar, mostly glucose, and some fructose and pectin that in
commercial operations could be an important by-product.
The tree, low-branching and bushy-but slender because of its upturned
limbs-reaches a maximum height of 8-10 m. Seldom grown in commercial
orchards, it is often planted in backyard gardens. The tree is easily propagated
by budding onto rootstocks of the same species. Seedlings or grafted plants
grow rapidly and bear fruit by the third year.


LIMITATIONS AND SPECIAL REQUIREMENTS

Adapted only to lowland areas, the soursop is widely planted in the tropics
below an altitude of 1,000 m. It requires an annual rainfall of 100 cm or
more. It will not tolerate dry, cold winds and, least hardy of the annonas, it
produces few fruits in chilly, mountainous areas. Though it will not tolerate
waterlogging, the soursop can be grown in a wide variety of soils.


Soursop fruit. (K. and J. Morton)


CI~t II U







UNDEREXPLOITED TROPICAL PLANTS


Soursop tree, Florida. (J. Morton)


Soursops are soft and perishable when ripe, and they ferment quickly.
Consequently, they are difficult to transport and are not exported as fresh
fruits.
The tree, unfortunately, is not prolific, the usual crop being only 12-24
fruits per tree. In Puerto Rico, production of 2%-4 tons of fruit per acre is
considered a good yield from well-tended trees. Generous fertilization will
increase the crop.
The flowers are pollinated by insects, usually beetles. Pollination by hand
encourages fruit-set because pollen is often shed before the stigma is
receptive, and small, malformed fruits result.
In very humid areas of El Salvador it has been observed that soursop trees
often grow well, but bear only a few poor-quality fruits. Most of their flowers
and young fruit fall due to anthracnose caused by the fungus Colletotrichum
gloeosporioides Penz. Anthracnose can be controlled with fungicides. Mealy
bugs, fruit flies, and red spiders are common pests, but can be controlled
with appropriate pesticides. In Surinam and Trinidad, fruit must be bagged to








FRUITS


avoid stunting and malformation caused by the soursop moth and soursop
wasp, which infest young fruit and seeds.
Soursop seeds are toxic, and care must be taken to assure that all are
removed before the pulp is processed.



RESEARCH NEEDS

The main research needs of soursop are agronomic. Agronomists should
investigate pollination and fruit-set problems thoroughly so that fruit
production can be improved.
A search should be made for prolific cultivars (with good horticultural
characteristics) that produce good-sized, low-fiber fruit with superior keeping
quality. Exceptionally large and well-formed soursops have been seen on the
market in Buga, Colombia, and Saigon, South Vietnam.


Selected Readings
Benero, J. R., A. J. Rodriguez, and A. Roman de Sandoval. 1971. A soursop pulp
extraction procedure. Journal of Agriculture. University of Puerto Rico.
55(4):518-19.
Benero, J. R., A. L. Collazo de Rivera, and L. M. I. de George. 1974. Studies on the
preparation and shelf-life of soursop, tamarind and blended soursop-tamarind soft
drinks. Journal of Agriculture. University of Puerto Rico. 58(1):99-104.
Leal, F. J. 1970. Notas sobre la guanabana (Annona muricata) en Venezuela. Proceedings
of the Tropical Regional American Society for Horticultural Science. Mexico.
14:118-21.
Morton, J. F. 1966. The soursop or guanabana (Annona muricata Linn.)Proceedings of
the Florida State Horticultural Society. 79:355-66.
Nakasone, H. Y. 1972. Production feasibility for soursop. Hawaii Farm Science.
21(1):10-11.
Payumo, E. M., L. M. Pilac, and P. L. Maniquis. 1965. The preparation and storage
properties of canned guwayabano (Annona muricata L.) concentrate. Philippine
Journal of Science. 94(2):161-69.
Sanchez-Nieva, F. 1970. Frozen soursop puree. Journal of Agriculture. University of
Puerto Rico. 54(2):220-36.


Research Contacts and Germ Plasm Supply
Food Technology Laboratory, University of Puerto Rico, Rio Piedras, Puerto Rico (J. R.
Benero)
Hawaii Agricultural Experiment Station, Honolulu, Hawaii 96822, USA (H. Y.
Makasone)
Jardin Botinico, Universidad del Valle, Cali, Colombia (V. M. Patifio)
University of the Philippines, College of Agriculture, Los Bafios, Laguna, Philippines
(R. V. Valmayor)







UNDEREXPLOITED TROPICAL PLANTS


UVILLA


Uvilla* (pronounced oo-vee-lya) is a small tree of the western Amazon
(Brazil, Colombia, Peru). It produces large racemes of purple, grape-like fruit
up to 4 cm wide, with a large pit and a sweet, white pulp. The fruit is
consumed raw and is also made into wine. It grows in wet equatorial forests
and could easily become pantropic. People living in the ecological environ-
ment where it grows have difficulty getting food. But uvilla is prolific; it
fruits heavily and over a long period-3 months or so-during the wet season;
few fruits (other than pineapple) grow well in similar wet equatorial forests.
This tree is recommended for testing as a home-garden crop throughout
the humid tropics.
A relatively fast grower, it begins to fruit in 3 years. The tree apparently
has few, if any, enemies. The tree is cultivated singly around the Indians'
houses. The fruit at the top of the tree ripens first. A forked branch is used to
knock it off.
Uvilla exploitation has been totally neglected by science. It has never been
the subject of an agronomic study, nor has any effort been made to establish
plantations. It is proposed here as a topic for small-scale testing rather than
for mass cultivation.
Related species, especially P. sapida, grow in the forest as wild trees. They
bear edible fruit, but little else is known about them.


LIMITATIONS AND SPECIAL REQUIREMENTS

Nothing whatever is known of the agronomic requirements of this plant. And
nothing is known of the composition and nutritive value of the fruit, except
that it is rich in sugars.
The skin is acrid and inedible and must be removed, but it peels off easily.
Uvilla is dioecious (pollen and fruit are born on different individual plants)
and care must be taken in commercial orchards to plant enough polliniferous
trees. In some regions, natives believe it is possible to distinguish the sex by
examining the seeds. This needs experimental confirmation.


RESEARCH NEEDS

A program for uvilla improvement should be initiated. It would not be costly.
All known regional varieties and strains (some may be distinct species) should
*Pourouma cecropiaefolia Mart. Also known as imbaaba do vinho, uva de monte,
caimar6n, Amazon grape, etc. Family: Moraceae.






























Uvilla fruit. (J. Zarucchi)



be assembled in one nursery for development and hybridization of the best
yielders, largest or sweetest fruit, fastest growers, etc.
Nutritionists should undertake research to identify the components and
food value of the fruit.
Nothing is known of uvilla's industrial potential-its processing, preserva-
tion, or use as a flavoring. Exploratory investigation to identify the potential
and problems could be rewarding.




Selected Readings
Ducke, A. 1946. Plantas de Cultura Precolombiana na Amazonia Brasileira. Notas Sobre
las Especies ou Formas Espontdneas que Supostamente Ihes Teriam Dado Origem.
Boletin Tecnico No. 8. Institute AgronBmico do Norte, Bel6m, Brazil.
Macbride, J. F. 1960. Flora of Peru. Fieldiana Botany. 13(1, pt. 5). Field Museum of
Natural History, Chicago, Illinois, USA.
Patifio, V. M. 1963. Plantas Cultivadas y Animales Domesticos en America Equinoccial-
Tomo I: Frutales. Imprenta Departamental, Cali, Colombia.
P6rez-Arbelaez, E. 1956. Plantas Utiles de Colombia. 3rd Ed., Libreria Colombiana-
Camacho Rold6n Cfa. (Ltda.), Bogota, Colombia.
Romero-Castafteda, R. 1961. Fruitas Silvestres de Colombia. Vol. I. Author, Bogoti,
Colombia.
Teixeira (sa Fonseca), E. 1954. Frutas do Brasil. Ministerio da Educaqao e Cultura.
Institute Nacional do Livro. Rio de Janeiro. Sedegra (Sociedad Edit8ra e Grafica
Ltda.)








UNDEREXPLOITED TROPICAL PLANTS


Uvilla tree in the Colombian Vaup6s. (J. Zarucchi)


,000p'W-








FRUITS 87


Research Contacts and Germ Plasm Supply
Institute Nacional de Pesquisas da Amaz6nia, Manaos, Brazil.
Ministerio de Agricultura, Bogota, Colombia.
Universidad del Vale, Cali, Colombia (V. M. Patifio) [specimens in the Estaci6n Agricola
de Palmira and Estaei6n del Calima]
Universidad Nacional de la Amazonia Peruana. Facultad de Ciencias y Humanidades,
Apartado 496, Iquitos, Peru. (C. S. Flores)




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