* Nematology (Botany) Circular No. 45
THE TUNG OIL TREE, ALEURITE;
K. R. Langdon
The tung oil tree, also known as tung nut or tung tree, Aleurites fordii Hemsl.
(fig. 1) is a native of China and has been cultivated there for around 4,000
years. It has been widely introduced and planted as an oil plant in warm tem-
perate areas of the world, including north Florida.
Fig. 1. Aleurites fordii (after West 1960)
Tung oil tree, Aleurites fordii: A small deciduous tree to 35 ft (11 meters)
tall and wide with smooth bark, mucilaginous sap, and thick twigs. Leaves
* alternate, long-stalked, simple; blades 5-10 in. (13-25 cm) long, broadly ovate
to subcordate, acute, and often with additional point each side of tip, mar-
gins entire, bases rounded to subcordate; petiole with two reddish or brownish
Contribution No. 189, Bureau of Nematology, P. 0. Box 1269, Gainesville, FL 32602
:. Agri.nt%4lC r Servi
WAR 26 1987
Uivefsity of Florida
glands near blade. Flowers in large terminal clusters in spring usually before
leaves. Flowers about 1 in. (25 mm) wide with 5-7 light pink or white petals
' marked with deep red or brownish red lengthwise lines and reddish brown bases,
Giving the overall appearance of a pink flower with a dark center. Each in-
florescence with sqepral'pistillate and numerous staminate flowers in the same
cluster. Fruits nearly lobular, 2-3 in. (50-75 mm) wide, dark green, turning
'r6wnrbon long drooping pedicels. Seeds 3-7, large, 1 in. (25 mm) long and
nearly as wide, hard, brown to black, rough-coated, flesh white.
Tung oil trees were first planted in Florida at Tallahassee in 1906. Since that
time around 40,000 acres have been planted for oil production from Gainesville
north and west. Over 12 million pounds of tung oil annually have been produced
in Florida in peak years. Tung oil has been considered one of the best drying
oils available for use in paints and varnishes. However, during the past 10 to
20 years synthetic resins have to a considerable extent replaced tung oil. The
resultant loss of market has caused many growers to abandon their plantings or
to bulldoze out the trees. The tung oil industry has virtually ended in Florida
with little or no production and very few tung oil products on the market.
Tung oil trees can still be seen in some of the old plantings, as seedlings in
fence rows, or as ornamentals in yard plantings. The spectacular spring floral
display makes tung trees desirable as ornamentals. The trees grow rapidly and
commence flowering after only a few years growth. Care should be exercised,
though, in the use of these trees because of their toxic properties.
The foliage, sap, and fruit (nuts), as well as commercial tung meal (residue
after oil extraction) and tung oil are irritant and contain a toxic saponin
which causes gastro-enteritis. This gastro-enteritis may be accompanied by mild
to violent purging. Vomiting, diarrhea, or both may be involved. In mild to
moderate cases, symptomatic treatment usually results in complete recovery.
Chewing a portion of a kernel and spitting it out produces irritation of the
mouth and lips lasting several hours and makes eating and swallowing quite dif-
ficult and painful. The minimum fatal amount for a human being has not been
determined. Finished tung oil products appear to be quite safe when used pro-
Hadsel, D. W. 1959. Tung oil industry in Florida. Fla. Dept. Agric. Bull.
Watt, J. M., and M. G. Breyer-Brandwijk. 1962. The medicinal and poisonous
plants of southern and eastern Africa. p. 395-397. E. & S. Livingstone.
West, E. 1960. Poisonous plants around the home. Agric. Ext. Serv. Bull. 175.