Leucaena leucocephala (Lam.) deWit.
Leadtree, Loa haole, Ekoa, Hediondilla, Zarcilla, Tanta, Jumbie bean
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
Leadtree is valued as an excellent protein source for cattle fodder, consumed
browsed or harvested, mature or immature, green or dry. The nutritive value is
equal to or superior to alfalfa. Leadtree has gained a favorable reputation in
land reclamation, erosion control, water conservation, reforestation and soil
improvement programs, and is a good cover and green manure crop. The leaves,
used as a mulch around other crops, are said to significantly increase their
yields. It is said to possess the power of extracting selenium from the soil
and concentrating selenium in the seed. This could be used to ameliorate
seleniferous soils if the feed were discarded or used for some purpose other
than feed. Seeds yield about 25 percent gum worthy of commercial
investigation. Seeds after softening are strung as beans into various items of
jewelry for tourists in Puerto Rico and the Virgin Islands. In the Philippine
Islands, young pods are cooked as a vegetable and seeds are used as a
substitute for coffee. Ripe seeds are sometimes eaten parched like popcorn.
Wood is hard and heavy (sp. gr. 0.7), the sapwood light yellow, the heartwood
yellow-brown to dark brown, used for fuel or charcoal. Plants are used in some
countries for shade for black pepper, coffee, cocoa, quinine, and vanilla and
for hedges. In many places, however, renegade seedlings have created a noxious
weed situation. The dipilatory chemical mimosine has been used, experimentally
at least, to shear sheep.
Medicinally, the bark is eaten for internal pain. A decoction of the root and
bark is taken as a contraceptive, ecbolic, depilatory, or emmenagogue in Latin
America. However, in experiments with cattle, leucaena had no effect on
Seeds and young leaves yield 4 percent of mimosine, which causes loss of hair
in non-ruminant animals, especially in horses, mules, donkeys and hogs. Leaves
also contain 0.08 percent of the glucoside quercetrin. Per g of N, there are
294 mg of arginine, 88 cystine, 125 histidine, 563 isoleucine, 469 leucine, 313
lycine, 100 methionine, 188 methionine + cystine, 294 phenylalanine, 231
threonine, 263 tryosine and 338 mg valine. Leucine protein makes a better
animal feed than copra in several amino acids, and is equivalent to alfalfa in
most of them. If leucaena makes up half the animals diet, problems result due
to mimosine (35 percent, on a dry-weight basis, of the protein). Heating the
leaves or adding ferrous sulfate reduces the mimosine or its toxicity. Raw
young leaves are reported to contain per 100 g edible portion: 68 calories,
79.5 percent moisture, 2.9 g protein, 0.8 g fat, 1S.3 g total carbohydrate, 1.8
g fiber, 1.5 g ash, 553 mg Ca, and 51 mg P. Raw, tender tops and pods contain
per 100 g edible portion: 59 calories, 80.7 percent moisture, 8.4 g protein,
0.9 g fat, 8.8 g total carbohydrate, 3.8 g fiber, 1.2 g ash, 137 mg Ca, 11 mg
P. 9.2 mg Fe, 4,730 mg b-carotene equivalent, 0.09 mg riboflavin, 5.4 mg
niacin, and 8 mg ascorbic acid. The genus Leucaena is also reported to
contain hydrocyanic acid, leucaenine, quercitrin and tannic acid.
Arborescent deciduous small tree or shrub, to 20 m tall, fast-growing; trunk
1025 cm in diam., forming dense stands; where crowded, slender trunks are
formed with short bushy tuft at crown, spreading if singly grown; leaves
evergreen, alternate, 1025 cm long, malodorous when crushed, bipinnate with
310 pairs of pinnae, these each with 1020 pairs of sessile narrowly oblong to
lanceolate, gray-green leaflets 12 cm long, less than 0.3 cm wide; flowers
numerous, axillary on long stalks, white, in dense global heads 12 cm across;
fruit pod with raised border, flat, thin, becoming dark brown and hard, 1015
cm long, 1.62.5 cm wide, dehiscent at both sutures; seeds copiously produced,
1530 per pod, oval, flattish, shining brown, 18,00024,000 per kg; taproot
long, strong, well-developed. Tree grown as an annual when harvested for
forage. Fl. and fr. nearly throughout the year.
Over 100 cvs and botanical varieties, and several closely related or synonymous
species contribute to the leucaena genepool. The commoner 'Hawaiian' type,
native to coastal Mexico, is now a widespread tropical weed. It is versatile
in adaptation and has become a serious weed in cultivated areas and wastelands.
The 'Salvador' type, less aggressive and more tall and tree like, producing
twice the biomass as the Hawaiian types. The 'Peru' type, treelike also,
branches low down on the trunk, it contains several cvs highly productive of
forage. There is quite a variability in mimosine content and cleaner cvs are
in order. Colombian cvs and Leucaena pulverulenta have much less
mimosine. Assigned to the Middle America Center of Diversity, leadtree or
cultivars thereof is reported to exhibit tolerance to aluminum, disease,
drought, high pH, heavy soil, laterite, light frost, limestone, low pH,
salt, slopes, weeds, and wind. (2n = 104, 36).
Native throughout the West Indies from Bahamas and Cuba to Trinidad and Tobago,
and from southern Mexico to northern South America. Naturalized northward to
southern Texas, California and southern Florida, and southward to Brazil and
Chile: also naturalized in Hawaii and the Old World tropics.
Requires long, warm, wet growing seasons, doing best under full sun. In
Indonesia it is grown to 1,350 m, in Java to 1,080 m. Natural stands are found
mostly below 500 m in areas of 617 dm rainfall. Its growth rate is slower, at
higher altitudes. About one dm per month is required for good growth. The
plant is known for its drought tolerance. The leadtree thrives on a wide range
of soils, but the most rapid growth is on deep clay soils which are fertile,
moist and alkaline. It tolerates aluminum and soils low in iron and
phosphorus. It grows best on neutral or alkaline soils, but does poorly on
acidic latosols unless Mo, Ca, S and P are added. Its deep root system permits
it to tolerate many soil types, from heavy soils to porous coral. Ranging from
Warm Temperate Dry to Moist through Tropical Very Dry to Wet Forest Life Zone,
leadtree is reported to tolerate annual precipitation of 1.8 to 41.0 dm (mean
of 30 cases = 14.9), annual mean temperature of 14.7 to 27.4°C (mean of 30
cases = 24.0°C), and pH of 4.3 to 8.7 (mean of 21 cases = 6.1).
Trees, propagated by seed or cuttings coppice well. Some seedlings less than
one-year old will produce viable seed. Seeds remain viable from several months
to several years. The hard waxy seedcoat makes scarification necessary before
planting. For forage, seed should be sown 2.57.5 cm deep, planting at onset
of wet season. Leadtree responds favorably to fertilizer and lime. Irrigation
and cultivation may be necessary. The crop soon produces a dense stand.
The crop can be cut at any stage for silage or fodder.
Leadtree produced 56 MT/ha/year green forage in Hawaii at 24 m altitude. With
adequate moisture yields of 80 MT/ha have been obtained. Two year old trees
have yielded 4.57 kg pods per tree. Duke (1981a) reported annual DM yields
are ca 220 MT/ha, equivalent to up to 4,300 kg protein per hectare, nearly
double the yields of alfalfa. In his pphytomass files, Duke (1981b) reports DM
yields of 213 MT/ha/yr in Australia, 1416 in Brazil, 1520 in Cuba, 35 in
Mauritius, 13 in New Guinea, 1519 in Taiwan and 321 in the Virgin Islands.
With its rhizobium, leucaena can fix more than 500 kg N/ha. On 3 to 8 year
trees, annual wood increments vary from 24 to over 100 m3/ha
averaging 30 to 40. Dry leucaena wood has 39% the calorific value of fuel oil
(10,000 cal/kg), lecaena charcoal 72.5%. In , Molokai, Hawaii (Brewbaker
1980) a 400-ha farm of Leucaena leucocephala on a four year rotation is
expected to fuel a two megawatt facility producing 11.6 million KWh/yr. This
will replace about 22,000 barrels of diesel. "Wood yields of the giant
Leucaena equal or exceed those of other tropical trees and can be the
equivalent annually of 30 barrels of oil per acre." Conservatively, rounding
their 22,000 barrels per year down to 20,000 barrels, or about half of Panama's
daily import, two 400-ha farms may satisfy one day's requirement for Panama,
and 730 400-ha farms may satisfy annual requirements or 292,000 ha.
Conservatively again, 300,000 ha of Leucaena could satisfy Panama's
current energy requirements, providing in the process more than 450,000 metric
tons of nitrogen-rich dry macter using the assumptions adopted by Brewbaker
(1980). (Curtis and Duke, 1982)
According to NAS (1977b) the fertilizer value of the "fines" is as follows:
Leucaena is relatively resistant to the pests and diseases prevalent in
Hawaii, but extensive plantation culture may invite the breakdown of this
apparent resistance. Twig borers, seed weevils and termites, as well as
damping off may hinder the plant. Herbivorous mammals may be fond of the
seedlings. Bananas may do better in the shade of leucaena than in full
sunlight due to reduced damage by Sigatoka disease.
Even under favorable conditions, continual brousing, or cutting and removing
the wood or foliage will deplete a Leucaena plant of some vital
nutrients; fertilization is then required, particularly P, S, Ca, Mo, and Zn.
"It adapts badly to acid soils. Lime pelleting addition of a special Rhizobium
strain as well as fertilizer containing Mo, P, S, and Ca are needed to get it
started. Leucaena also grows poorly in high-alumina soil-5 and requires
careful fertilization with phosphate and calcium. With fertilization, good
yields are possible in aluminous soils." Small lateral roots near the soil
surface carry Nitrogen-fixing Rhizobium nodules which are usually 2.515 mm in
diameter, frequently multiobed. Functioning nodules are bright pink inside.
The Leucaena-Rhizobium partnership is capable of annually fixing more than 500
kg/i (200 metric tons/400 ha). In 1974 Panama consumed 14,400 MT Nitrogen,
probably imported. Apparently IRHE and RENARE have discussed using Eucalyptus
for their fuel farms, with seed from Australia. Presumably the seeds will be
from species or ecotypes adapted to Tropical Moist Forest of Darien. Many
species of Eucalyptus may not adapt to such tropical heat and humidity
conditions. Leucaena may be more adapted to the climate if not the
soil. Many ecologists and foresters would recommend first an examination of
the native species already adapted to an area, then consider the existing
introduced species before introducing new aliens. Too often the alien species,
introduced without its natural enemies, may propagate and invade to become a
weed. Almost all species recommended to us as a biomass candidate including
many of the botanochemical species have great weed potential.
Complete list of references for Duke, Handbook of Energy Crops
- Brewbaker, J.L. (ed.). 1980. Giant leucaena (Koa haole) energy tree farm: An
economic feasibility analysis for the island of Molokai, Hawaii. Hawaii Natural
Energy Institute, Univ. of Hawaii, Manoa. (HNEI-80-06). 90 p.
- Curtis, C.R. and Duke, J.A. 1982. An assessment of land biomass and energy
potential for the Republic of Panama. vol. 3. Institute of Energy Conversion.
- Duke, J.A. 1981a. Handbook of legumes of world economic importance. Plenum
- Duke, J.A. 1981b. The gene revolution. Paper 1. p. 89150. In: Office of
Technology Assessment, Background papers for innovative biological technologies
for lesser developed countries. USGPO. Washington.
- N.A.S. 1977b. Leucaena: promising forage and tree crop for the tropics.
National Academy of Sciences, Washington, DC.
Last update Wednesday, January 7, 1998 by aw