3009

11: Auxiliary plants

Erythrina variegata L.

Herb. Amb.: 10 (1754); Amoen. acad. 4: 122 (1759).

LEGUMINOSAE - PAPILIONOIDEAE

2n = 42, 44

Erythrina indica Lamk (1786), Erythrina orientalis (L.) Murr. (1787), Erythrina variegata L. var. orientalis (L.) Merrill (1917).

Indian coral tree, variegated coral tree (En). Indian coral bean (Florida), tiger's claw (Am). Arbreau corail, arbre immortel (F). Indonesia: dadap blendung (Sundanese), dadap ayam, (Javanese), dede bineh (Madurese). Malaysia: dedap, cengkering. Papua New Guinea: balbal (Kuanua, Pala), valval (Lamekot), banban (Ugana). Philippines: karapdap (Tagalog), andorogat (Bikol), bagbag (Ilokano). Burma (Myanmar): penglay-kathit. Cambodia: roluöhs ba:y. Laos: (do:k) kho, th'o:ng ba:nz. Thailand: thong baan, thong phueak (northern), thong laang laai (central). Vietnam: c[aa]y v[oo]ng nem, h[af]i d[oof]ng b[if] (Annamese), dan ro, (Thuân Hai).

Erythrina variegata is a native of the coastal forests from East Africa, the Indian Ocean Islands, from India, throughout South-East Asia, to the Pacific Islands and the Northern Territory and Queensland in Australia. It has been in cultivation throughout the tropics for so long that its original dispersal as a beach species is now obscure.

In India, Malaysia and Indonesia Erythrina variegata is used as live support for betel (Piper betle L.), black pepper (Piper nigrum L.), vanilla (Vanilla planifolia H.C. Andrews) and yam (Dioscorea spp.) vines. When planted as a live fence the more prickly forms are best. In southern India, it is occasionally grown as a shade tree for cocoa and coffee; in Java it is not recommended for this purpose as it is leafless for up to a few months per year. A columnar cultivar is planted in hedges as a wind-break. The leaves are used as green manure and to a limited extent as fodder.
Boiled leaves are eaten as a pot-herb. The raw seeds are poisonous but may be eaten after boiling or roasting.
The leaves and bark are widely used as cures in many South-East Asian countries. The bark is used as an antipyretic in Burma (Myanmar), in decoction to treat liver problems in China and intermittent fever in Indonesia. A decoction of the bark and leaves is used to treat dysentery in Indonesia; sweetened, it is considered a good expectorant. A decoction of the leaves may also be used to treat mastitis. The bark has also been used to treat rheumatism and to relieve asthma and coughs. The roots and leaves are often employed to alleviate fever in the Philippines. Crushed seeds are used to treat cancer and abscesses in Indo-China, and are boiled in a little water as a remedy for snake bites in Malaysia. In India, the root and bark are called 'paribhadra', one of the reputed drugs of Ayurvedic medicine.
The wood is of little use, even as firewood, but can be turned into packing-cases. In New Britain, it is used for spears and shields. The wood has been tested as a source of pulp for the paper industry. The fibre is acceptable for pulping, having good length, high flexibility and slenderness ratio and low Runkel's ratio. The light, spongy wood is used in Cambodia as floats for fishing-nets. Erythrina variegata is also planted as an ornamental tree, the leaves of the variegated forms and the flowers being very showy. In New Britain, blackened dried leaves are worn for their scent.

Leaves of Erythrina variegata contain per 100 g dry matter 1.5 g N, 1.5 g K, and 0.15 g P. Leaves and seeds have narcotic properties. Alkaloids are present in low concentrations. Seeds contain hypaphorine, erysodine, and erysopine, the leaves and bark the poison erythrinine, acting on the nervous system. Saponins are present in leaves, bark and seeds. Hydrocyanic acid has been found in the leaves, stems, roots, and fruits. The seed contains 0.75% of the free amino acid histidine, an amount only paralleled by Erythrina fusca Loureiro.
The wood is white and soft, spongy, fibrous and darker towards the centre. Growth rings are visible. The density of the wood is 300 kg/m³.

Deciduous tree, 3—27 m tall with fluted bole and much branched crown; trunk and branches thick and sappy, armed with large, scattered prickles; bark grey or grey-green, furrowed; young shoots stellate pubescent at first, later glabrous; flowering branches often leafless; in cultivation tree often unarmed. Leaves alternate, trifoliolate; stipules lanceolate, 1—1.5 cm long, caducous; petiole 2—28 cm long, unarmed; rachis 10—12 cm long; petiolule up to 1.5 cm long, at base with globose glandular stipels; leaflets ovate to broadly rhomboid, usually wider than long, 4—25 cm x 5—30 cm, terminal one largest, base rounded or slightly cordate, apex acuminate, entire or sometimes shallowly lobed, thinly coriaceous, green or sometimes strikingly variegated light green and yellow, glabrescent. Inflorescence an axillary, dense raceme 10—40 cm long, ferruginous tomentose, lateral near the top of branchlets; peduncle 7—25 cm long; pedicel up to 1.5 cm long; flowers in groups of 3 scattered along the rachis, large, bright red (occasionally white); calyx eventually deeply spathaceous, 2—4 cm long, glabrescent, red; standard ovate-elliptical, 5—8 cm x 2.5—3.5 cm, more than twice as long as wide, shortly clawed, longitudinally conduplicate, recurved, bright red without white veins; wings and keel subequal, 1.5—2.5 cm long, red; stamens 10, monadelphous, 5—7 cm long, vexillar stamen basally connate with the tube for 1 cm, red; pistil with pubescent ovary and glabrous style. Pod sausage-shaped or long cylindrical, 10—45 cm x 2—3 cm, 1—13-seeded, slightly constricted between the seeds, glabrescent, distinctly veined and exocarp bursting irregularly, indehiscent. Seed ellipsoid to reniform, 6—20 mm x 5—12 mm, smooth, glossy black, purplish or purplish red-brown.

Erythrina variegata can live to about 100 years. Unpruned trees may attain a height of 15—20 m in 8—10 years. Subsequently, the growth rate slows down, but the main stem continues to increase in diameter. Erythrina variegata forms root nodules and fixes atmospheric nitrogen with Bradyrhizobium bacteria. In general, rooting is superficial, with most roots in the upper 30 cm of the soil; older trees, however, root deeper.

Erythrina variegata has the typical 'bird flowers' of Erythrina spp.: scentless, strong and elastic to withstand birds hopping about and poking into the flowers. The flowers in the drooping inflorescences are upturned, which prevents the copious nectar from running out. The flowers remain open for 2—3 days, but stop secreting nectar after the morning of the first day.
Forms with variegated leaves have been classified as botanical varieties; subclassification of the species, however, seems most appropriate at the cultivar level. A cultivar with a columnar habit has been selected. It possibly originated in New Caledonia, from where it spread to other tropical and warm temperate areas, including Hawaii and Florida. It was released in the United States in 1985 as cv. Tropic Coral.

Erythrina variegata is adapted to coastal forests, but is frequently cultivated inland, up to 1200 m altitude. Annual rainfall should exceed 1250 mm. The mean minimum temperature should be about 20°C, the mean maximum temperature about 32°C. As in Erythrina fusca, the seeds float and are dispersed by ocean currents.

Erythrina variegata is usually propagated from large cuttings, 2—3 m long and 5—8 cm in diameter, to ensure that new shoots are above grazing height and to allow fast early growth. Branch cuttings with the terminal bud are sometimes used in India to obtain tall, straight-stemmed trees. Propagation by seed is also possible. Seed germinates in 8—10 days, attaining a transplantable height of 30—50 cm in 8—10 weeks.
In India, a spacing of 8—10 m is used when planting Erythrina variegata for shade in coffee plantations; spacing of live stakes for betel and pepper is 2—3 m x 2 m.

When trees are used to support vines, side branches are lopped at intervals of 6—8 weeks, the foliage being used as green manure or fodder. When planted for shade, lower branches are removed immediately after establishment and only a few high branches are allowed to grow. Subsequently, the trees are pollarded once per year in the middle of the rainy season.

In Hawaii the trees are attacked by powdery mildew (Oidium sp.), Chinese rose beetle (Adoretus sinicus), mealy bugs (Phenacoccus spp.), mites (Tetranychus cinnabarinus and Polyphagotarsonemus latus). Like other Erythrina spp., it is a potential host of the fruit-piercing moth (Othreis fullonia), the hibiscus snow scale (Pinnaspis strachani), and the carob moth (Ectomyelois ceratoniae) as well as of their predators. In India, larvae of the beetle Raphipodus damage the roots.

Yields depend on the pruning system. In India, trees used as support for betel vines yield 15—50 kg fodder per year; shade trees in coffee plantations produce about 100 kg fodder and 25—40 kg wood per year.

Erythrina variegata is included in the Erythrina germplasm collection at Waimea, Hawaii. No breeding programmes are known to exist.

Erythrina variegata is useful as a live fence and source of fodder. It is also a handsome ornamental. It may be used as raw material for the pulp wood industry. Its medicinal value needs further investigation.

Hegde, N.G., 1993. Cultivation and uses of Erythrina variegata in Western India. 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 Associaton, Paia, Hawaii, United States. pp. 77-84.
Mitra, R. & Srivastava, U.C., 1985. Pharmacognostical study of root and bark of Erythrina indica Lam. Paribhadra. Bulletin of the Botanical Survey of India 27: 75-85.
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. 22-24.
Rotar, P.P., Joy, R.J. & Weissich, P.R., 1986. 'Tropic Coral' tall Erythrina. Hawaii Institute of Tropical Agriculture and Human Resources, Honolulu, Hawaii, United States. 10 pp.
Shakya, R., 1988. Indigenous nitrogen-fixing trees in the farmlands of Nepal. In: Withington, D., MacDicken, K.C., Sastry, C.B. (Editors): Multipurpose tree species for small farm use. Proceedings of an international workshop held from November 2-5, 1987, in Pattaya, Thailand. Winrock International Institute for Agricultural Development, Morrington, Arkansas, United States and International Development Research Centre, Ottawa, Canada. pp. 125-130.
Soto-Hernandez, M. & Jackson, A.H., 1994. Erythrina alkaloids: isolation and characterization of alkaloids from several Erythrina species. Planta Medica 60: 175-177.
Subramanyam, S.V., 1987. Assessment of utility of some pulp wood species of Kerala State based on fibre quality. The Indian Forester 113(6): 427-433.
Verdcourt, B., 1979. A manual of New Guinea legumes. Botany Bulletin No 11. Office of Forests, Division of Botany, Lae, Papua New Guinea. pp. 425, 427-428.

B. Na-songkhla

Na-songkhla, B., 1997. Erythrina variegata L.. In: Faridah Hanum, I & van der Maesen, L.J.G. (Editors): Plant Resources of South-East Asia No 11: Auxiliary plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea