Botany Circular No. 30 Fla. Dept. Agric. & Consumer Services
January/February 1996 Division of Plant Industry
Comparison of Two Parasitic Vines:
Dodder (Cuscuta) and Woe Vine (Cassytha)1
Alan R. Haynes2, Nancy C. Coile3 and Timothy S. Schubert4
INTRODUCTION: "Dodder" is a name often applied to two genera of parasitic vines: Cuscuta (Convolvulaceae)
and Cassytha (Lauraceae). Cuscuta is a pure (obligate) parasite of plants because dodder plants lack chlorophyll
(Mabberley 1987). Cassytha is a hemiparasite of plants because Cassytha plants do contain chlorophyll and can pro-
duce some carbohydrates for the plant's nutrition. Each is potentially severely damaging or fatal to a wide spectrum
of host plants attacked (Wellman 1972; Agrios 1988; Dawson et al. 1994).
Despite great taxonomic differences, these two species are very similar in appearance and cause confusion even
among trained observers. Both have thin, yellow-to-orange colored viny stems, and are virtually leafless and root-
less. Cassytha's green stems will become orangish with age (Fig. 1). Cuscuta stems are smoother and hava more
shiny appearance than Cassytha, which has ridged stems. When crushed, a pungent scent is released by Cassytha,
while Cuscuta is odorless. The fruits of Cuscuta are dry, with black seeds, while Cassytha has juicy white berries.
Still, identification is best left to specialists under most circumstances.
For convenience, we will refer to Cuscuta as "dodder" and Cassytha as "woe vine." Both are known by a variety of
common names, including vampire vine, devil's guts, scald, and love vine (Mabberley 1987; Wellman 1972;
FAMILY DIFFERENCES: Dodder is a member of the Convolvulaceae family which includes 58 genera, such as
morning glory (Ipomoea spp.) and many other vines, herbs and trees (Mabberley 1987). Jacquemontia reclinata
House (Convolvulaceae) is a federally-endangered herbaceous species (U.S. Fish and Wildlife 1993). Dodder con-
sists of ca. 145 species which are all cosmopolitan (Mabberley 1987). All but 52 excluded species are on the FDACS
Noxious Weed List (FDACS/DPI Rule 5B-57.007). Wunderlin (1982) lists six species of dodder in Central Florida;
Clewell (1985) lists two additional species, but lacks two of the Central Florida species; Long and Lakela (1971) list
three and one is an additional species. There are, consequently, a total of nine species for Florida.
Woe vine is in the family Lauraceae, which is comprised of mostly shrubs and trees such as laurel (Laurus nobilis
L.), red bay (Persea borbonia (L.) Spreng.), avocado (Persea americana Mill.), and cinnamon (Cinnamomum verum
J. Presl). Notice that many of the members of Lauraceae (including woe vine) are fragrant when stems or foliage are
crushed. The 16 species of woe vine are native to the Old World tropics (Mabberley 1987), but have become wide-
spread throughout Europe and the Americas. Cassythafiliformis L. is the only species listed for Florida and occurs
south of the area around Tampa Bay and Cape Canaveral (Wunderlin 1982). Worldwide, C. filformis is frequently
found near tropical beaches and will tolerate submergence in salt water for 14 days (Wellman 1972).
COMPARISONS: Dodder grows four to five times faster than woe vine and becomes permanently attached in
about three days as compared to eight days for woe vine (Wellman 1972). Dodder has been observed completing
four wraps around a bean plant in seven hours (Wellman 1972). Both woe vine and dodder attack host plants by
attaching with their growing tips (Wellman 1972; Agrios 1988). Dodder rapidly dissolves surface cells of the host
plant and then attaches by haustoria; woe vine more slowly (Burnett 1979; Agrios 1988; McRitchie 1990).
Haustoria (Fig. 2) are specialized plant structures of parasitic plants that penetrate a host cell and absorb material
from the host (Bold 1967); these are similar to the fungal haustoria. Both parasitic vines literally suck food and water
I Contribution No. 34, Bureau of Entomology, Nematology and Plant Pathology Botany Section.
2 Plant Protection Specialist. FDACS, Division of Plant Industry, 100 S. Mulrennan Road #6. Valrico, FI 33954-3559,
3 Botanist, FDACS, Division of Plant Industry, P.O. Box 147100, Gainesville, FL 32614-7100.
4 Plant Pathologist, FDACS, Division of Plant Industry, P. O. Box 147100, Gainesville, FL 32614-7100.
from the stems and leaves of host plants. Both vines penetrate into the stems of the host plant where they grow along-
side phloem cells (Wellman 1972). Although both have tiny flowers (less than 0.5 cm across for Cuscuta), the flower
structure differs markedly (Fig. 3).
While dodder is an annual and woe vine a perennial, this fact is often of little consequence in tropical climates in the
absence of a hard freeze. Dodder and woe vine may overwinter in fields on seed or debris. Seeds of these parasitic
plants send up rootless shoots during growing periods. If no host is found, the parasite vine goes dormant for a few
weeks, but eventually dies without a host. If contact is made and the host plant is penetrated, the base of the para-
site vine shrinks, shrivels up, and all contact with the ground is lost (Agrios 1988). A single dodder vine may pro-
duce up to 3,000 seeds (McRitchie 1990). When the capsule bursts open seeds are thrown out in a circle ten feet in
diameter (McRitchie 1990).
In a simulated "war of the vampire vines", Wellman (1972) found dodder to consistently overwhelm woe vine,
repeatedly killing tips of woe vine. Dodder will even double back on itself, using its own tissues to allow bud and
flower formation. Both vines suffered detrimental effects when they contacted the parasitic mushrooms, Polyporus
IMPORTANCE: Dodder and woe vine may kill plants to the roots, and are potential invaders of virtually all green
plants including food crops (Dawson et al. 1994). While dodder tends to attack herbaceous plants and woe vine
woody plants, exceptions are numerous for each. Wheeler et al. (1989) describe Cuscuta exaltata Engelm., tree dod-
der, as a parasite on Quercus virginiana Mill, live oak.
Both woe vine and dodder can be vectors of plant diseases. For example, viruses, fungi, MLOs/phytoplasmas, and
bacteria (e.g., the tumor-producing crown gall Agrobacterium tumefaciens (E.F. Sm & Town.) Conn) can be passed
from woe vine and/or dodder into their plant hosts (Wellman 1972, Tsai 1980).
Cuscuta species are listed as mandatory quarantine items by the Division of Plant Industry, Florida Department of
Agriculture and Consumer Services. However, the Noxious Weed List (FDACS/DPI) from Rule Chapter 5B-57
specifically lists 52 species of Cuscuta as not being noxious weeds.
CONTROL: Control of either dodder or woe vine is difficult and most often drastic in nature. Infested plants quick-
ly become unsalvageable (Dawson et al. 1994). Parasite and victim should be removed and burned or buried in soil
two feet or more (Agrios 1988). Woe vine, if found in large trees, may sometimes be successfully pruned out.
Preventative chemical controls noted by Agrios (1988) include Dacthal (DCPA), a preemergent herbicide. The
1996 Weed Control Manual (Meister 1996) also lists Dacthal for control of dodder. Dacthal is labeled for use on
ornamentals in Norcini (1995) and is commonly available at garden supply stores (Norcini, personal communica-
tion). Always consult current labels for latest use and safety instructions and requirements. Such treatments might
prevent recurrence after an infestation.
Agrios, G.N. 1988. 3rd ed. Plant pathology. Academic Press, New York, NY. 803 p.
Bold, H.C. 1967. 3rd ed. Morphology of plants. Harper and Row, New York, NY. 668 p.
Burnett, H.C. 1979. Woe-vine, a parasitic weed. Florida Department of Agriculture and Consumer Services,
Division of Plant Industry, Gainesville. Plant Pathology Circular No. 201. 2 p.
Clewell, A.F. 1985. Guide to the vascular plants of the Florida Panhandle. Florida State University Press,
Tallahassee. 605 p.
Dawson, J., LJ. Musselman, I. Dorr, and P. Wolswinkel. 1994. Biology and control of Cuscuta. Reviews of
Weed Science 6: 265-317.
Florida Department of Agriculture and Consumer Services, Division of Plant Industry. 1995. Rule Chapter 5B-
57.007. 4 June.
Long, R.W. and 0. Lakela. 1971. A flora of tropical Florida. University of Miami Press, Coral Gables. 962 p.
Mabberley, DJ. 1987. The plant-book. Cambridge University Press, Cambridge. 706 p.
McRitchie, JJ. 1979. Dodder, a parasitic plant pest. Florida Department of Agriculture and Consumer Services,
Division of Plant Industry, Gainesville. Plant Pathology Circular No. 334, Aug. 2 p.
Meister, R.T. 1996. Weed Control Manual. Meister Publishing Company, Willoughby, OH. 538 p.
Norcini, J.G. 1995. Preemergent herbicides for use on ornamentals. Fact Sheet ENH-94, Mar.: 179-185. In: D.
Colvin (ed.). 1995 Florida Weed Control Guide. SP-53. University of Florida, Institute of Food and
Agricultural Sciences. Florida Cooperative Extension Service, Gainesville.
Tsai, J. 1980. Lethal yellowing of coconut palm: search for a vector. p. 189. In: Harris, K. F. and K. Maramorosch
(eds). Vectors of plant pathogens. Academic Press, New York, NY.
U.S. Fish and Wildlife Service. 1993. Endangered and threatened wildlife and plants: determination of endangered
status for a Florida plant, Jacquemontia Reclinata. Federal Register 58 (225): 62046-62050.
Wellman, F.L. 1972. Tropical American plant disease (neotropical phytopathology problems). The Scarecrow Press,
Inc., Metuchen, NJ. 989 p.
Wheeler, J., G.C. Wheeler, and K.R. Langdon. 1989. Cuscuta exaltata on Quercus virginiana. Florida
Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville. Botany Circular
No. 24. 2 p.
Wunderlin, R.P. 1982. Guide to the vascular plants of Central Florida. University of South Florida Press, Tampa.
Fig.l. Tangled Cassytha stems vining around an unknown herba-
ceous stem. The arrow indicates a flower (see Fig. 3,B).
Fig. 2. Cassytha on an oak leaf. Three haustoria
(parasitic connections) are indicated by arrows.
(Thanks are extended to Cindy S. Kamelhair for
providing the plant material for photography.
Photography credits: Jeffrey W. Lotz.).
Fig. 3. A) Cluster of Cuscuta flowers. B) Solitary, 3-valvate
flowers of Cassytha.