Chinese Tallow Tree

Biodiesel Magazine reports on a new potential biodiesel feedstock, the Chinese tallow tree. It is said to be a potential algae-as-feedstock rival if yield reports of 1,000 gallons of oil per acre are true. Although it is known as an invasive nuisance tree, it does have potential for oil extraction from both its seeds and its woody biomass. In its native Asia, the tree is already used for a wide variety of product including everything from transfat-free shortening to silk dye. In America, though, it could pose big problems because of its invasiveness which is regulated by USDA’s Farm Bill, making it potentially unused unless changes in its presence and development are strong enough evidence to support its research and use. However, farmers contend that they know how to keep the crop under control while allowing it to be more productive on its current lands. Primarily found in the south and along the Gulf Coast, it is a hardy and tolerant tree with 45 to 60 percent oil yield from its seeds alone. In other countries, the tree is well-maintained and consistent; however, being wild in the U. S., its oil content and usefulness can vary greatly, making it potentially unreliable if harvested from wild growth. Overall, the tallow tree holds great promise in its oil-for-biodiesel content, so research is underway on how to use this plant to its fullest ability. Time will tell which view wins in this debated tree’s usefulness.

Chinese Tallow Tree

This tree is native to southern China, where a substantial industry once revolved around the harvesting and processing of its waxy seeds. They were thrown into boiling water to remove the wax, which was skimmed off and used to make candles. The seeds were then pressed to extract an oil for use in lamps, as a purgative, and for making oil-paper and soap. These days Chinese tallow tree is grown mostly as an ornamental, and it is one of the few deciduous trees to produce good autumn colour in areas with mild winters.

Plant details

Common name: Chinese tallow tree

Botanic name: Sapium sebiferum

Description

This is a deciduous tree to around 8m (25') tall with a medium domed crown. In autumn the mid-green leaves turn crimson, with some yellow, orange and ruby-red foliage. In November and December greenish yellow flower spikes appear on the tips of the branches, followed by 3-celled capsules. The fruit ripens and turns brown in autumn, then splits open to reveal three seeds which are covered with a layer of pure white wax.

Best climate

Chinese tallow tree grows from cool to subtropical zones. Grow in a warm sheltered microclimate in frost prone areas and protect trees when young.

Zone
Zones 8, 9, 12-16, 18-21, 25-31, H1
 
Full Sun
Full
 
Regular Water
Moderate
 
Toxicity
Milky sap is poisonous if ingested

Grows 30 to 40 ft. tall, 25 to 30 ft. wide, with a dense, round or conical crown. Tends toward shrubbiness, multiple trunks, and suckering but is easily trained to a single trunk. In colder areas, branch tips may freeze back in winter, but new growth will quickly cover damage. Leafs out late in spring. Foliage is dense but flutters in the slightest breeze, giving tree an airy look. Light green leaves are roundish, tapering to a slender point; with moderate autumn chill, they can turn flaming red, plum purple, yellow orange, or mixed colors. For good color, select a tree while it is in fall leaf. Spikes of tiny yellowish flowers at branch tips are followed in fall by clusters of small fruits with a waxy grayish white coating.

Good points

beautiful orange, red, purple and yellow autumn foliage provides autumn colour in climates with mild winters good street tree or small tree for the home garden insect and disease free drought tolerant once established

Downside

like other members of the family Euphorbiaceae, the stems contain an irritant milky sap birds disperse the seeds, which germinate easily, sometimes in places where they are not wanted!

Care

Chinese tallow tree will grow in most soils, but prefers a well-drained sandy loam enriched with organic matter. Water well until the tree becomes established. Plant in a warm sunny position for best autumn colour.

Getting started

Plants for sale are usually grown from seed and the colour of their autumn display will vary greatly. To make sure you know exactly how your tree will perform buy one in autumn. Chinese tallow trees are widely available at nurseries, or ask your nursery to order one for you. Prices range from $13 for a 200mm (8") pot up to $700 for an advanced 200 litre tree 2.5m tall.

Further reading

'The Garden Plants of China' by Peter Valder, (1999). Florilegium, ISBN 1876314028, rrp $88.

Copyright 2001 CTC Productions

Uses

Chinese tallow tree is cultivated for its seeds as a source of vegetable tallow, a drying oil and protein food, and as an ornamental. Fruits yield two types of fats: outer covering of seeds contain a solid fat with low iodine value, known as Chinese Vegetable Tallow; kernels produce a drying oil with high iodine value, called Stillingia Oil. Tallow is used for manufacturing candles, a layer of wax being placed over the tallow body to prevent too rapid burning; has excellent burning quality, and gives an inodorous clear bright flame; also used for making soap, cloth dressing and fuel. Pure tallow fat is known in commerce as Pi-yu. Oil is used in making varnishes and native paints because of its quick-drying properties, in machine oils and as a crude lamp oil. Pure oil expressed from the inner part of the seeds is known in commerce as Ting-yu. Oil cakes made from crushed seeds with tallow and oil together is known as Mou-yu. Residual cake, after oil is expressed, is used as manure, particularly for tobacco fields. Wood is white and close-grained, suitable for carving and used for making blocks in Chinese printing; also used for furniture making and incense. Chinese prepare a black dye by boiling leaves in alum water. Tree grows rapidly, developes an attractive crown, and, as leaves turn red in fall, is cultivated as a shade or lawn tree about houses. It is used as a soil binder along roads and canals. Chinese place an insect on the tree to feed; it lays eggs in the seed, making some of the "jumping beans," because of movements of larvae inside.

Folk Medicine

In Chinese medicine, oil is used as purgative and emetic, not as a usual vegetable oil for humans. Overdose of native medicine probably would cause violent sickness and perhaps death. Additionally, Chinese use the plant as an alexeteric, suppurative, and vulnerary, especially for edema and skin ailments. Decoction of the root bark used for dyspepsia, considered tonic. Resin from root bark considered purgative. The latex is an acrid and powerful vesicant.

Chemistry

The fatty acid composition of the oil is: caprylic, 1.50; capric, 1.00; myristic, 0.97; palmitic, 2.80; stearic, 1.00; oleic, 9.40; linoleic, 53.40; and linolenic, 30.00%. A Hong Kong sample contained 26.8% oil, with: capric, traces; palmitic, 7; stearic, 3; 2,4-decadienoic, 5; oleic, 7; linoleic, 24; and linolenic, 54%. Stillingia oil is considered superior to linseed oil in its drying and polymerizing properties, probably due to the presence of 2,4-decadienoic acid. Seed meal, left after the extraction of oil, possesses a high content of protein, and is a valuable feed and fertilizer. It can be processed into a refined flour, containing 75% protein, fit for human consumption. The amino acid composition of the protein is as follows: arginine, 16.6; aspartic acid, 11.7; cistine, 1.3; glycine, 4.9; glutamic acid, 17.3; histidine, 2.9; leucine, 7.4; lycine, 2.6; methionine, 1.6; tyrosine, 3.7; and valine, 7.8%. The vitamin-B content of the flour compares favorably with that of wheat-flour. The flour, supplemented with lysine and methionine, is reported to be superior to wheat-flour. Ethanol extraction of powdered root bark yielded 0.1% phloracetophenone 2,4-dimethylether, and reethanol extraction gave xanthoxylin (C10H12O4). The bark also contains moretenone, moretenol and a new triterpene, 3-epimoretenol. Leaves contain gallic and ellagic acids, isoquercitrin, and tannin (5.5%) (C.S.I.R., 1948–1976).

Description

Small to large deciduous tree, 10–13 m tall (in 30 years), often with a gnarled trunk, bark gray to whitish-gray with vertical cracks; stem exudes a milky poisonous juice; leaves alternate, broad rhombic to ovate, 3.5–8.5 cm long, 4–9 cm wide, cordate-acuminate at apex, usually round at base, turning orange to scarlet in autumn, falling early in the cold season; petioles 1.5–7 cm long, with 2 conspicuous glands at apex and on each side of scale-like bracts; flowers monoecious, greenish-yellow, in terminal spikes, 5–10 cm long; fruit a capsule, subglobose, 0.95–1.7 cm in diameter, 3-valved, with three seeds coated with a white wax; seeds half-ovate, 0.6–1.0 cm long, 0.43–0.6 cm wide, 0.5–0.77 cm thick, with an acrid penetrating taste. Fl. April–June; fr. ripens September–October.

Germplasm

Of the many cvs cultivated, more than 100 are found in Taiwan. Two main types are 'Eagle-Claw' and 'Grape', varying according to form of fruit-spikes, fruit-sprigs, fruit stalks and maturing period. (2n = 36)

Distribution

Native to many provinces of central China, especially north of the Yangtze Valley, and Japan, Chinese tallow tree is also cultivated there and on Hainan Island, Hong Kong, Taiwan and Korea. It has been introduced and naturalized into Sri Lanka, and introduced to Indochina, Bengal, India, Sudan, Martinique, southern United States (S. California, S. Arizona, and Texas to Florida, north to South Carolina), southern France and Algeria.

Ecology

Adapted for growing on canal banks, on steep mountain slopes, granite hills or sandy beaches, it grows in alkaline, saline or acid soils. Said to thrive in alluvial forests, on low alluvial plains, and on rich leaf-molds, growing best in well-drained clayey-peat soils. Favorable climatic conditions are mean air temperatures of 12.5 to 30.1°C, and an annual precipitation from 13 to 37 dm. It is a subtropical to warm temperate plant. It is hardy and able to withstand a few degrees of frost, but unripened twigs are susceptible to frost injury. It will grow at elevation of 100 to 800 m.

Cultivation

Propagated by seed, cuttings, layering or top-grafting on seedling stock. Seed usually sown in late autumn or early spring. Seedlings in the first year may grow 0.3–0.9 m in height and should be transplanted. When seedlings are about 1 m tall (in the spring of the third year), they should be planted out in permanent areas. Tree grows rapidly, 5 to 8.5 m tall with DBH of 13–17 cm in 10 years, and 10–13 m tall with DBH 30–40 cm in 20 to 30 years. When cultivated, trees are grown in plantations or transplanted to borders of fields or canals, so as not to interfere with the cultivation of the soil. Chinese also make cuttings by breaking small branches and twigs, care being taken not to tear or wound the bark. These are layered and rooted.

Harvesting

Fruits and seeds, about the size of a pea, are harvested by hand in November and December when leaves have fallen. Plants require from 3–8 years to bear, but then contiue to bear for years, averaging 70–100 years. Trees attain full size in 10–12 years. Seed can be threshed from the tree and collected by hand (once estimated at less than three cents per kg). Mechanical methods may be readily adapted to the harvest. When fruit is harvested by hand in midwinter, they are cut off with their twigs with a sharp, crescent-shaped knife attached to the end of a long pole, which is held in the hand and pushed upward against the twigs. The capsules are pounded gently in a mortar to loosen the seeds from the shells, from which they are separated by sifting.

Yields and Economics

In plantations trees should be planted one rod apart each way, giving 400 trees per hectare, and if trimmed to a convenient size for hand-harvesting, would yield 14 MT seed/ha, containing 2.6 MT oil, 2.8 MT tallow, 1.5 MT protein concentrate, 1.1 MT fibrous coat, and 4.5 MT shell. Oil, tallow and protein meal would bring about $750 per hectare. This yield could increase with age. Scheld et al (1980) report yields of 4,000 to 10,000 kg/ha, and cite estimates of 25 barrels of oil per year as a sustained energy yield. Tallow is separated by placing the seed in hot water, thereby melting the tallow which floats on the surface, or by melting tallow with steam and collecting it when it drops off. Solvent extraction of the tallow from the seed is also used, tallow still adhering to the seed being removed by an alkali treatment. The fairly thick hard shell prevents extraction of the oil inside, so that the seed is crushed and Stillingia Oil is obtained by pressing or solvent extraction. According to one report, seed contains about 20% oil, 24% tallow, 11% extracted meat, 8% fibrous coat and 37% shell. Oil keeps well and probably need not be refined. Seed yields vary with the variety and age-gradations of the trees, a tree averaging at five years of age 0.453 kg, at 10 years, 3.379 kg and at 20 years, 11.989 kg; yields gradually decreasing after that. Meal, obtained by the extraction of the kernel, has a pleasant nut-like flavor, is white and contains 76% protein. Yields of Stillingia Oil as high as 53% of the kernel have been reported in some varieties. Flour and protein of Chinese tallow nut contain vitamin B (Thiamin). In China and other Oriental countries, as in other regions of the world, large quantities of tallow and oil are extracted annually from this tree. Tallow mills are erected in vicinities where the tree is extensively grown. In addition to its economic value (from $750/ha for the oil, tallow and protein), the tree is extensively propagated for ornamental purposes. From 200,000–300,000 trees are grown for ornamental purposes alone in Houston, Texas.

Energy

Coppicing well, the tree grows rapidly, the mean annual girth increment 2.6–5.2 cm. The wood, weighing only 513 kg/cu m is used for fuel. With some tolerance to salt, the tallow trees should be investigated as energy crops for saline situations. Princen (1979), assuming an annual oil yield of 25 barrels per hectare, estimates that only 24 million hectares of Sapium would be required to produce a replacement for the ca 8% of our petroleum usage which goes into chemical production. That means 300 million ha could replace all our petroleum useage (ca 35% of Brazil, 108% of Argentina, 32% of the USA). Specific gravity of the wood ranges from 0.37–0.48 (mean 0.44) in samples from 18- to 24-yr-old trees. Energy values range from 7,226–7,835 Btu/lb (mean 7,586) (Scheld and Cowles, 1981). Rapidity of coppicing, taproot production, drought and salt tolerance, and rapid growth rate are attributes leading Scheld and Cowels (1981) to regard the tree as a promising biomass candidate (in the warm coastal region of the United States) which can be established over large acreages by conventional agricultural planting methods and which can provide woody biomass for direct burning or conversion to charcoal, ethanol, or reethanol.

Biotic Factors

Flowers are favored by honey-bees and fruits are readily eaten by birds, including domestic fowl. It has been considered a desirable plant for bird-food. Tree is remarkably free of insect pests. The root-knot nematode, Meloidogyne javanica has been reported (Golden, p.c. 1984). Fungi known to attack this tree include: Cercospora stillingiae, Clitocybe tabescens, Dendrophthoe falcata, Phyllactina corylea, Phyllosticta stillingiae, and Phymatotrichum omnivorum.

References

  • C.S.I.R. (Council of Scientific and Industrial Research). 1948–1976. The wealth of India. 11 vols. New Delhi.
  • Princen, L.H. 1977. Potential wealth in new crops: research and development. p. 1–15. In: Seigler, D.S. (ed.), Crop resources. Academic Press, Inc., New York.
  • Scheld, H.W. and Cowles, J.R. 1981. Woody biomass potential of the Chinese tallow tree. Econ. Bot. 35(4):391–397.
Complete list of references for Duke, Handbook of Energy Crops