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Euphorbia tirucalli L.

Euphorbiaceae
Petroleum plant, Aveloz, Milk bush

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Ecology
  7. Cultivation
  8. Harvesting
  9. Yields and Economics
  10. Energy
  11. Biotic Factors
  12. References

Uses

Probably most familiar as a subtropical and tropical ornamental, aveloz has recently made popular headlines as a potential "cancer cure" and more important, as an energy source. Growing in rather arid zones as well as more mesophytic zones, the species makes a good living fence post. A large shrub, Euphorbia tirucalli, is used as a hedge in Brazil. According to Calvin, these plants grow well in dry regions or land that is not suitable for growing food. He estimates that the plants might be capable of producing between 10 and 50 barrels of oil per acre. Cut near the ground, they would be run through a mill like a cane crushing mill, while the plants would regrow from the stumps. Crude obtained from these plants would run $3.00 to $10.00 per barrel. Calvin discussed this concept with Petrobas, the Brazilian national petroleum company, which is investigating. Calvin's most exciting statement, if true, would be a boon to Brazil and the United States. "He estimates, assuming a yield of 40 barrels per acre (100 barrels per hectare) that an area the size of Arizona would be necessary to meet current requirements for gasoline" (in the U.S.). (Science 194: 46, 1976). The latex is toxic to fish and rats. Africans regard the tree as a mosquito repellent. In Ganjium, rice boiled with the latex is used as an avicide. Aqueous wood extracts are antibiotic against Staphylococcus aureus. The wood, weighing 34 pounds per cu. ft., is used for rafters, toys, and veneer. The charcoal derived therefrom can be used in gun powder. Since the latex contains rubber, whole plant harvesting seems most advisable from an energy point-of-view (if the tree coppices well) with rubber, petroleum, alcohol as energy products, and resins, which may find use in the linoleum, oil skin, and leather industries. In Brazil, Euphorbia gymnoclada, very similar to tirucalli (both are called aveloz), is much used for firewood. One cu. m. of wood yields 2 kg latex with the fibrous residue usable for paper pulp.

Folk Medicine

Recently (SPOTLIGHT July 14, 1980) Alec de Montmorency kindled long-sleeping interests in aveloz (Euphorbia spp. including tirucalli) inferring that it "seems to literally tear cancer tissue apart." Several Brazilian Euphorbias, E. anomala, E. gymnoclada, E. heterodoxa, E. insulana, E. tirucalli, known as aveloz, have local notoriety as cancer "cures," and often find their way into the U.S. press as cancer cures. I fear they are more liable to cause than cure cancer. Still the following types of cancer are popularly believed in Brazil to be alleviated by aveloz: cancer, cancroids, epitheliomas, sarcomas, tumors, and warts. Hartwell (1969) mentions E. tirucalli as a "folk remedy" for cancers, excrescences, tumors, and warts in such diverse places as Brazil, India, Indonesia, Malabar and Malaya. The rubefacient, vesicant latex is used as an application for asthma, cough, earache, neuralgia, rheumatism, toothache, and warts in India. In small doses it is purgative, but in large doses it is an acrid irritant, and emetic. A decoction of the tender branches as also that of the root is administered in colic and gastralgia. The ashes are applied as caustic to open abscesses. In Tanganyika, the latex is used for sexual impotence (but users should recall "the latex produces so intense a reaction ... as to produce temporary blindness lasting for several days." In Zimbabwe, one African male is said to have died of hemorrhagic gastroenteritis after swallowing the latex to cure sterility.) The root is used as an emetic for snakebite. In Malabar and the Moluccas, the latex is used as an emetic and antisyphilitic. In Malaya, the stems are boiled for fomenting painful places. The pounded stem is applied to scurf and swelling. In the Dutch Indies, pounded stems are used as a poultice for extracting thorns. The root infusion is used for aching bones, a poultice of the root or leaves for nose ulcers and hemorrhoids. The wood decoction is used for leprosy and for paralysis of the hands and feet following childbirth. Javanese use the latex for skin complaints and rub the latex over the skin for bone fractures.

Chemistry

The latex contains 53.8–79.9% water and water solubles and 2.8–3.8% caoutchouc. Fresh latex contains a terpenic alcohol, isoeuphoral (C30H50O) identical with euphol from Euphorbia resinifera. Dried latex contains no isoeuphorol but a ketone euphorone (C30H48O). Taraxasterol (C30H50O.CH3OH) and tirucallol (C30H50O) have also been isolated. Resin, however, is the principle constituent (75.8–82.1%) of the dried latex. According to Hager's Handbuch (List and Horhammer, 1969–1979), the stem contains hentriacontene, hentriacontanol, the antitumor steroid b-sitosterol, taraxerin, 3,3'-Di-O-methylellagic acid, ellagic acid, and a glycoside fraction which hydrolyses to give kampferol and glucose, and a ca 0.1% sapogenin acetates. The whole plant contains 7.4% citric acids with some malonic and some bernstein (succinic) acids.

Description

Dioecious, succulent, cactus-like milky tree, devoid of spines, to 10 m tall, the branches often arranged in pseudowhorls. Leaves small, early deciduous, alternate, 1–2.5 cm long, ca 3–4 mm broad, oblanceolate, acute at tip, tapered to the sessile base. Flowers in yellow head, stalkless at the end of twigs.

Germplasm

Reported from the African Center of Diversity, aveloz, or cvs thereof, is reported to tolerate drought, poor soil, sand, and slope.(2n = 20)

Ecology

Ranging from Tropical Thorn to Moist through Subtropical Thorn to Moist Forest Life Zones, the milkbush is reported to tolerate annual precipitation of 2.5 to 40 dm (mean of 6 cases = 11), and estimated to tolerate annual temperature of 21 to 28°C, and pH of 6 to 8.5. Calvin suggests that it grows well where annual precipitation is 2.5 to 5 dm and where there is no frost. Ive seen it as a cultivar in almost every tropical site I have visited.

Cultivation

According to Melvin Calvin, Euphorbia tirucalli "will grow in the same soils sugarcane will grow in, even without irrigation" (Gogerty, 1977). Calvin notes that 5 cm cuttings take readily and increased one-thousand fold in one growing season, attaining more than 50 cm height in the first growing season (Calvin, 1980).

Harvesting

Harvested in 1978, the 5 cm cuttings that grew to more than 50 cm, weighed roughly 2 kg and produced the equivalent of 15 barrels of oil per acre. It could be mowed, or possibly after reaching full size, tapped (Calvin, 1980). For energy purposes, Calvin suggests they be "cut near the ground and run through a crushing mill in much the same fashion as if done with sugarcane... The plants themselves would regrow from the stumps, so replanting might be necessary only once every 20 years or so." (Maugh, 1976).

Yields and Economics

As early as 1941, French scientists (Steinheil, 1941) reported yields of 3 MT oil per hectare from a similar Moroccan species, Euphorbia resinifera (10,000 liters latex/ha). In 1976, Calvin "optimistically estimates that the cost of crude hydrocarbons obtained in this manner would be somewhere between $13 and $10 per barrel. The oil furthermore, would be practically free of sulphur and other contaminants." (Maugh, 1976). California associates of Calvin have since projected $150 to $200 per barrel for Euphorbia oil. Philip Leakey, from Kenya, claims to be getting 400 MT biomass (fresh weight = 85% moisture) per ha in Kenyan areas with a rainfall of ca 20 inches per year. I can see 60 MT DM in a several year old stand but do not think Dr. Leakey meant to imply that these were annual yields. Leakey claims to be getting, now, 20 MT/ha charcoal from similar plantations, renewably. Such figures, if replicated, should be very encouraging to arid land inhabitants (Philip Leakey, personal communication, September 28, 1981).

Energy

Back in 1976, Melvin Calvin was quoted as saying the plants might be capable of producing 10 and 50 barrels of oil per acre per year (Maugh, 1976). Back in 1977, Melvin Calvin was quoted as saying, "A cultivated field would yield the equivalent of 2 to 20 barrels of crude oil per acre per year, possibly for as little as $3 per barrel. OPEC oil costs three times that much." (Gogerty, 1977). Back in 1979, Calvin was quoted as saying the growth was 1,000 fold when 5 cm cuttings were inserted in the field. Calculations by a Japanese firm, based on plantings in Okinawa, showed the possibility of producing 5–10 barrels of oil per acre per year. Calvin (1980), however, quotes these same sources as 10–20 barrels per acre.

Biotic Factors

Dehgan and Wang describe the plant as having "no natural enemies". Golden (p.c. 1984) notes that Meloidogyne may affect the plant.

References

Complete list of references for Duke, Handbook of Energy Crops
Last update Tuesday, January 6, 1998 by aw