Erythrina subumbrans (PROSEA Auxiliary plants)
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Introduction |
Erythrina subumbrans (Hassk.) Merrill
- Protologue: Philip. J. Sci. Bot. 5: 113 (1910).
- Family: Leguminosae - Papilionoideae
- Chromosome number: 2n = 42
Synonyms
- Erythrina lithosperma Miquel (1855),
- Hypaphorus subumbrans Hassk. (1858),
- Erythrina hypaphorus Boerl. (1899).
Vernacular names
- December tree (En).
- Indonesia: dadap duri (general), dadap rangrang (Sundanese), dadap ri (Javanese) (armed forms); dadap minyak (general), dadap lesang (Sundanese), dadap lenga (Javanese) (thornless forms).
- Malaysia: dedap batik, cengkering.
- Papua New Guinea: dadap.
- Philippines: dap-dap (Tagalog), rarang (Bikol), anii (Bisaya).
- Burma (Myanmar): ye-katit.
- Laos: th'o:ng hla:ng.
- Thailand: thonglang-pa (northern), thong-lang (central).
Origin and geographic distribution
E. subumbrans occurs naturally from India and Sri Lanka, throughout South-East Asia (except New Guinea) to Fiji and Samoa. Now it is distributed throughout the tropics.
Uses
E. subumbrans was one of the most widely planted shade trees for coffee and other crops in Indonesia, until large numbers of trees were destroyed by a root disease in the late 19th Century. It is still planted on a smaller scale in Indonesia for shade in cocoa, coffee and tea plantations, and as live support for betel (Piper betle L.), pepper (Piper nigrum L.) and vanilla (Vanilla planifolia H.C. Andrews) vines. In Malaysia, it is used as a shade tree for coffee and tea; in Western Samoa, as a shade tree for cocoa and taro (Colocasia esculenta (L.) Schott) and as a live support for yams (Dioscorea spp.). In Burma (Myanmar) and India, it is often grown to support betel and pepper vines. In Sri Lanka, it is the most common shade tree for tea and cocoa.
Very young leaves are steamed and eaten in salads in Java.
The leaves are a good and palatable fodder but if eaten by rabbits it can cause sterility and death. In Western Samoa, an addition of 5% leucaena meal and 5% dried and ground dadap meal to the starter diets of chicken improved their gains in weight.
Bark and leaves are used medicinally, sometimes mixed with parts of other plants. A decoction of the bark is taken to treat spleen afflictions in the Philippines. In Indonesia pounded young leaves are used as a poultice for women soon after giving birth and against headache; juice of leaves is used as an eye-wash and a decoction of the leaves is given for coughs.
The wood is utilized in canoe and raft building. In Papua New Guinea, trees are planted near villages for their showy red flowers, while in certain districts (e.g. Morobe) they are used in ritual ceremonies.
Properties
Loppings of E. subumbrans provide a quickly decomposing green manure, containing per 100 g dry matter: N 1.5-3 g, P 0.2-0.35 g, K 1-2 g. Flowers contain large quantities of nectar and are a major source of food for birds during the dry season in East Java. Seeds contain the curare-like alkaloids erysoline, erysopine and erythratine.
The wood of E. subumbrans is soft and light, with an air-dry density ranging from 335--385 kg/m3. The sapwood is not differentiated from the heartwood, which is light straw-coloured. Texture is coarse and uneven due to the presence of broad rays and abundant confluent parenchyma conspicuous to the naked eye. Grain is straight, shallowly interlocked or spiral. Growth rings are absent. Vessels are about 310 μm in diameter, few, solitary, in radial groups of 2 to 3.
Description
- A deciduous, medium-sized tree, 5-25 m tall, trunk reaching 60 cm in diameter; crown spreading; bark whitish; trunk and branches armed with stout prickles, in cultivation mostly unarmed.
- Leaves alternate, trifoliolate; stipules orbicular, small, caducous; rachis 10-21 cm long, inclusive of the petiole of 8-16 cm which is thickened at the base; petiolule up to 7 mm long; stipels 2, below the lateral leaflets, stipitate, cup-like, glandular, 2 mm long; leaflets ovate-triangular-rhomboid, terminal one largest and 8-16 cm × 6-14 cm, base rounded or cordate, apex acuminate, glabrous.
- Inflorescence racemose, in the upper leaf axils, 5-23 cm long, brownish-tomentose; flowers many, arranged in groups of 3; peduncle terete, robust, 3-15 cm long, pubescent; pedicel 2-3 mm long, in fruit up to 6 mm; calyx campanulate, 1-1.5 cm long, splitting open up to halfway down, tomentose, yellow-green; petals 5, red; standard broadly elliptical, shortly clawed, 2.5-4 cm × 2-3 cm, scarlet, at base inside with numerous white stripes; wings as long as the keel or slightly longer, about 1.5 cm long, pale red with a blackish upper margin; stamens 10, 3-3.5 cm long, monadelphous but vexillary stamen slightly shorter than other ones and only connate for the lower 0.5-1 cm, pinkish red; pistil with hairy ovary. Pod flat, curved, 10-15 cm long, on a slender stalk 3-4.5 cm long, lower part seedless and 2-2.5 cm wide, upper part thicker, 1-1.5 cm wide and 1-5-seeded, septate between the seeds, dehiscent. Seed ellipsoid, 7-18 mm × 5-11 mm, smooth, dull black.
Growth and development
E. subumbrans forms large numbers of effective root nodules. In Singapore it flowers from October to December during the height of the wet season. In Java, flowering and fruiting occur almost throughout the year, with peaks in February-March and October-November. Thornless forms generally produce fewer flowers and fruits than the armed, wild ones. As in other Erythrina spp., the red, odourless, nectar-rich flowers are so constructed that cross-pollination is universal. Pollination is by birds which feed on the abundant nectar.
Some of the leaves are shed during the dry season. However, in Java, trees are never completely leafless. Pruning before the start of the dry season can prevent leaves being shed during the dry season. Cultivated thornless forms may reach an age of 40-50 years but often die earlier because of diseases and pests.
Other botanical information
Most Erythrina spp. are ecologically separated, even when occurring in the same geographical region. Hybrids, however, occur frequently in cultivation, as there appear to be no barriers to interspecific hybridization. An unarmed hybrid between E. subumbrans and E. variegata L., named "dadap Solo"", probably originated near Surakarta in Java, and is widely planted. It is shorter than other unarmed forms of E. subumbrans, has a denser crown and rarely produces viable seed.
The necklace-shaped pods of E. subumbrans are highly characteristic and can be used to identify the species.
Ecology
E. subumbrans occurs at low and medium altitudes, from (0-)300-1500 m, in moist valleys, near streams, in open locations and secondary forest. It requires a high annual rainfall with a maximum of 4 months with less than 100 mm rainfall, and a mean annual temperature above 22 °C. It is reported, however, to occur gregariously on the Ijen plateau in East Java, in open grassland in stony or sandy, occasionally dry places; elsewhere it is widely dispersed. The trees are fairly tolerant of wind, unless branches have been damaged by borers. Seeds are dispersed by water and occasionally by birds.
Propagation and planting
E. subumbrans grows easily from large cuttings, even if they are 25 cm in diameter. It can be propagated by seed, but seedlings of thornless trees are generally armed. The spacings employed depend on the spacing of the main crop, pruning regime, and growth rate of the trees. In Western Samoa, a spacing of 1.5 m × 1.5 m is used in cocoa, 2 m × 2 m when planted as a shade for taro.
Husbandry
Pruning and pollarding are very well tolerated. In tea plantations in Sri Lanka it is customary to pollard twice a year. In coffee and tea plantations in Java, pruning is generally done once a year. The frequency of lopping depends on the requirements of the main crop, the labour supply and the growth rate of the trees and can be up to 4 times per year. However, mortality may occur if pruning is followed by a prolonged dry spell. Where E. subumbrans is pruned, it is sometimes used as a medium level shade tree, interplanted with taller shade trees like Paraserianthes falcataria (L.) Nielsen or Grevillea robusta Cunningham ex R. Br. Elsewhere, E. subumbrans is not pruned and is used for high shade, interplanted with Leucaena leucocephala (Lamk) de Wit providing low shade.
In Western Samoa, yam vines planted in a circle around an E. subumbrans tree are allowed to cover the canopy and suppress its growth.
Diseases and pests
At the end of the 19th Century in Java, E. subumbrans was heavily attacked by a root disease, which locally destroyed all trees and prevented its further planting. Little has been published about this disease, its cause and importance today.
The fungus Septobasidium bogoriense often grows on the bark. It does not cause direct damage, but keeps the bark moist, creating favourable conditions for pathogenic fungi like Corticium salmonicolor, Fomes spp., and Ustulina zonata.
Several boring insects attack the wood and bark of branches, often causing them to break and making them susceptible to rot. The leaves of E. subumbrans are damaged by many insects and defoliation is common. Normally, the trees recover rapidly.
Prospects
Where E. subumbrans is not too seriously affected by diseases and pests, it is one of the best shade and live support trees for a wide range of crops. It is fast growing, fixes atmospheric nitrogen, provides easily decomposing litter and its shade can be well adjusted to the requirements of the main crop. A programme for the selection of disease-tolerant cultivars would be well justified. Its neat appearance makes it a good ornamental and amenity tree.
Literature
- Brennan, E.B., 1992. A new grafting technique for Erythrina, Leucaena, and possibly other nitrogen fixing tree species. Nitrogen Fixing Tree Research Reports 10: 85-88.
- Chee, T.Y. & Ridwan, S., 1984. Fast growing species of trees suitable for urban roadside and shade planting. Malaysian Forester 47(4): 263-269.
- Filius, A.M., 1982. Economic aspects of agroforestry. Agroforestry Systems 1: 29-39.
- Kay, D.E., 1970. The production and marketing of pepper. Tropical Science 12: 201-206.
- Martin, F.W., 1984. Edible leaves from nitrogen fixing trees. Nitrogen Fixing Tree Research Reports 2: 57-58.
- Nguyên Van Thuân, 1979. Leguminosae-Papilionoideae, Phaseoleae. In: Aubréville, A. & Leroy, J.F. (Editors): Flore du Cambodge, du Laos et du Vietnam. Vol. 17. Muséum National d'Histoire Naturelle, Laboratoire de Phanérogamie, Paris, France. pp. 25, 27.
- Raharjo, Y.C. & Peter, R.C., 1985. Palatability of tropical tree legume forage to rabbits. Nitrogen Fixing Tree Research Reports 3: 31-32.
- Rogers, S., Iosefa, T. & Rosecrance, R., 1993. Development of an Erythrina-based agroforestry system for taro cropping in Western Samoa. In: Westley, S.B. & Powell, M.H. (Editors): Erythrina in the New and Old Worlds. Nitrogen Fixing Tree Research Reports, Special Issue. Nitrogen Fixing Tree Association, Paia, Hawaii, United States. pp. 200-204.
- Seibert, B., 1988. Living poles for pepper (Piper nigrum L.) in East Kalimantan: first growth of living poles of Gliricidia sepium (Jacq.) Walp. and Erythrina lithosperma Miq., and dead poles of Bornean ironwood (Eusideroxylon zwageri Teijs. and Binn.), and experiences with on-farm trials in transmigration settlements. Forestry and Forest Products. Report 8. German Forestry Group. pp. 9-15.
Author
- Umi Kalsom Yusuf
