3007

11: Auxiliary plants

Erythrina fusca Loureiro

Fl. Cochinch.: 427 (1790).

LEGUMINOSAE - PAPILIONOIDEAE

2n = 42

Erythrina glauca Willd. (1801), Erythrina ovalifolia Roxb. (1832), Erythrina atrosanguinea Ridley (1911).

Purple coral-tree, coral bean, swamp immortelle (En). Bucayo (Am). Bois immortelle, immortelle blanc (Fr). Indonesia: cangkring (Javanese, Sundanese), rase, kane (southern Sulawesi). Malaysia: dedap, dadap. Papua New Guinea: maor (Lamekot), vatamida (Ugana). Philippines: anii (Tagalog), korung-korung (Bisaya). Cambodia: roluöhs phâ-'aông. Laos: th'o:ng hla:ng. Thailand: thonglang nam, thonglong (central). Vietnam: v[oo]ng d[oo]ng (Ho Chi Minh City), v[oo]ng gai (Quang Nam), c[aa]y son dong (Annamese).

Erythrina fusca is the most widespread species in the genus Erythrina L. occurring wild in both the Old and New World tropics. In Asia and Oceania it occurs along coasts and rivers from India to the Philippines, New Guinea and Polynesia; in Africa in Madagascar, the Mascarene Islands, the Comoro Islands and Pemba Island, but not in continental Africa; in Central and South America in the West Indies, throughout the Amazon basin, and along the coast of Brazil, Colombia, up to Honduras and Guatemala. It is now planted throughout the humid tropics.

Erythrina fusca is widely planted as a shade tree in cocoa and coffee plantations in Central and South America and, less frequently, in South-East Asia. In Sumatra and Central America, pepper and vanilla vines are commonly planted with Erythrina fusca as live stakes. In Costa Rica, Erythrina fusca is occasionally used in live fences, though much less commonly than Erythrina berteroana Urban and other Erythrina spp. In Central America it is used as a source of fodder.
The young leaves are eaten as a vegetable in Java and Bali, the flowers in Guatemala. In Indonesia the bark is used for poulticing fresh wounds, and bark or root decoctions against beri-beri. Like many Erythrina spp. it is often planted for ornamental purposes.

The edible portion of the leaves contains per 100 g dry matter: 20—22 g crude protein; in vitro digestibility ranges from 30—55%. The mineral content of the leaves per 100 g dry matter is: N 3.2 g, P 0.15 g, K 1.0 g, Ca 1.3 g, Mg 0.5 g.
As in other Erythrina spp., the seed contains very small amounts of free amino acids and large amounts of alkaloids. In Erythrina fusca, only the amino acid histidine occurs in fairly large amounts (0.6—1.0%), which is characteristic of the species. The only common Erythrina alkaloids found in Erythrina fusca are erysotrine, erythraline, erysodine, erysovine and erysopine. Ant-repellent compounds in the nectar have been reported.
The weight of 1000 seeds is 200—700 g.
The wood is soft with a moderately coarse texture and an unattractive, straight grain. Growth rings are absent, axial and radial parenchyma fairly abundant. The colour of the wood is white to yellow, without differentiation between the heartwood and the sapwood. The average air-dry density ranges from 250—300 kg/m³.

A medium to large, spreading tree, 10—15(—26) m tall, crown rounded; trunk short, spiny (spines 1—2 cm long), much branched, sometimes buttressed to 2 m; bark brownish-grey or olive-brown, flaky. Branches spreading, spiny; branchlets stout, spineless or aculeate. Leaves alternate, trifoliolate; stipules and stipels orbicular, caducous; petiole up to 25 cm long, sometimes sparsely prickly; rachis up to 5 cm long, petiolule up to 1.5 cm; leaflets ovate to elliptical, 2.5—20 cm x 1.5—15 cm, subcoriaceous, rounded or subacute at both ends, pale green above, glaucous or greyish-green beneath, glabrous to velvety hairy. Inflorescence racemose, terminal, appearing when leaves are present, with pale brick-red or salmon (seldom white) flowers in fascicles scattered along the rachis, covered with deciduous, ferruginous hairs, mostly unarmed; peduncle up to 13 cm long; rachis 8—30 cm long; pedicel up to 2 cm long; bracts and bracteoles ovate, up to 2.5 mm x 2 mm, deciduous; calyx asymmetrical, broadly campanulate, about 1.5 cm long, lacerate or subentire but with a 0.5—1.5 mm long spur on the keel side, pubescent; standard rounded-rhombic, 4—7 cm x 3.5—6 cm, reflexed, orange or scarlet, broadly folded down the middle, claw 9 mm long; keel slightly longer than the wings, both about half the length of the standard; stamens 10, 4—6 cm long, 1 free, 9 united in lower half into staminal tube; pistil 4—6 cm long, ovary densely pubescent. Fruit a woody, linear, compressed pod, 14—33 cm x 14—18 mm, dehiscent, slightly constricted between the 3—15 seeds, stipe stout, 1.5 cm long, beak 2 cm long, velvety ferruginously hairy when young, later glabrescent. Seed oblong-ellipsoid, 12—18 mm x 5—8 mm, dark brown or black.

Young plants nodulate well under natural conditions. Trees flower when in leaf, and flowers are frequently visited and pollinated by birds. Fruits mature in approximately two months.

Trees nearly devoid of spines exist and have also been bred. Hybridization is frequent where several Erythrina species co-occur.

Erythrina fusca is found from sea level up to 2000 m altitude, within a wide range of rainfall patterns, from 1200 mm to over 3000 mm annually, with or without a seasonal distribution. Average daily temperatures range from 16—24°C at the higher elevations to over 26°C in the lowlands. It seems to prefer littoral locations with badly drained soils like swamps and stream banks and upland riverine marshes. In low-lying freshwater swamps Erythrina fusca attains huge dimensions and sometimes develops almost pure stands. In an experiment in Cauca, Colombia, on an acid soil of pH 4.3 and an aluminium saturation of 80%, it showed better growth than Samanea saman (Jacq.) Merrill and Delonix regia (Bojer ex Hook.) Rafinesque, which are considered tolerant of such conditions.
Seeds of Erythrina fusca float in water and are dispersed by ocean currents. They have been found on the beaches of cays of the Great Barrier Reef of Australia. Erythrina fusca and Erythrina variegata L. were among the first species to colonize Krakatau Island (Indonesia), only a few years after the cataclysmic eruption in 1883.

When used as a shade or nurse tree, Erythrina fusca is propagated by large cuttings, about 2 m long and 6—10 cm in diameter. Rooting success is excellent, provided soil moisture is close to field capacity. Cuttings start sprouting in 2—4 weeks. Erythrina fusca can also be propagated easily by seed. Fresh seed has a germination rate of 80—95%. In Costa Rica, trees supporting black pepper vines are planted at a density of 1600 trees/ha.

Established trees withstand regular pruning very well. They start sprouting rapidly and develop strong shoots. In Mexico, when shading cocoa, Erythrina fusca is managed under a moderate regime of pruning. Trees are partially pollarded once every 1—2 years, leaving a few branches per tree to regulate light influx to the crop. In the per-humid, tropical lowlands of Costa Rica, on alluvial soil, a 6-month pollarding cycle is used for trees supporting black pepper vines (Piper nigrum L.). Annual dry matter production from prunings of 1600 trees/ha (without natural litter fall) is 3.4 t/ha, corresponding to an N application of 124 kg/ha.
In Bahia, Brazil, it was observed that cocoa trees planted near Erythrina fusca produced more pods than those growing further away from the shade trees. Increased litter fall in plantations with Erythrina fusca added to the available amounts of N and P in the system, while daily evapotranspiration was reduced from 90 l/tree in unshaded cocoa trees to 40 l/tree in shaded trees on sunny days. On overcast days, the reduction was about 40%, from 45 l/tree to 26 l/tree.

Under conditions of high relative humidity the bark of Erythrina fusca may be attacked by fungi such as Calostibe striipora.
In pepper plantations in Sumatra, stakes of Erythrina spp. are frequently attacked by stem-borers. The damaged stakes may fall over and the pepper will not produce fruits properly. Two species of borer insects have been found, a stem-borer (Batocera sp.) and a ring-borer (family Lecanidae).
In alley cropping, Erythrina spp. may act as a host to diseases and pests of the associated crops. In Peru, the use of Erythrina spp. in alley cropping has already been discouraged due to an increase of shoot and fruit borers. In India, an increased number of root-knot nematodes (Meloidogyne incognita) has been observed in cardamom plantations with Erythrina fusca.

A collection of Erythrina spp. of over 70 entries has been established at the Waimea Arboretum in Haleiwa, Hawaii. The Tropical Agricultural Center for Research and Training (CATIE) in Turrialba, Costa Rica, maintains a collection of 28 species of Erythrina. Both collections include Erythrina fusca.

A breeding and selection programme is in progress at CATIE. Cultivars are being selected for absence of spines, branching habit, biomass characteristics for livestock fodder and capacity to retain their leaves during the dry period.

Erythrina fusca may be of special interest in the development of agroforestry systems for the per-humid tropics, due to its adaptability, ease of propagation from cuttings, ability to withstand regular pruning, and the rapid sprouting and development of shoots. However, diseases and pests should be monitored closely, as they may affect both Erythrina fusca and the associated crops. The feasibility of using it as a nurse tree for other tree species in reforestation projects in the tropics is an alternative to be explored.

Baretta-Kuipers, T., 1982. Wood structure of the genus Erythrina. Allertonia 3(1): 53-69.
de Oliveira Leite, J. & Valle, R.R., 1990. Nutrient cycling in the cacao ecosystem: rain and throughfall as nutrient sources for the soil and cacao tree. Agriculture, Ecosystems and the Environment 32: 143-154.
Gillett, J.B., Polhill, R.M. & Verdcourt, B., 1971. Erythrina. In: Milne-Redhead, E. & Polhill, R.M. (Editors): Flora of tropical East Africa. Leguminosae 4, Papilionoideae 2. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. p. 547.
Krukoff, B.A., 1939. The American species of Erythrina. Brittonia 3: 224-227.
Muschler, R.G., Nair, P.K.R. & Menendez, L., 1993. Crown development and biomass production of pollarded Erythrina berteroana, E. fusca and Gliricidia sepium in the humid tropical lowlands of Costa Rica. Agroforestry Systems 24: 123-143.
Neill, D.A., 1988. Experimental studies on species relationships in Erythrina (Leguminosae: Papilionoideae). Annals of the Missouri Botanical Garden 75: 886-969.
Russo, R.O., 1990. Erythrina: a versatile nitrogen-fixing woody legume genus for agroforestry systems in the tropics. Journal of Sustainable Agriculture 1(2): 89-109.

R.O. Russo & N.T. Baguinon

Russo, R.O. & Baguinon, N.T., 1997. Erythrina fusca Loureiro. 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