Peltophorum dasyrhachis (Miq.) Baker

A usually deciduous tree, up to 30 m tall, with a straight trunk and rather diffuse crown; root system with well-developed taproot and few superficial lateral roots; trunk up to 70 cm in diameter; bark up to 10 mm thick, reddish-brown inside; young branches reddish-tomentose, glabrescent. Leaves bipinnate, with 5-9 pairs of pinnae and 6-16 pairs of leaflets per pinna; stipules large, bipartite, branches pinnatifid or bipinnatifid; petiole up to 7 cm long, rachis up to 40 cm long, both reddish-pubescent; leaflets oblong-elliptical, 10-25 mm x 4-10 mm, sessile, base acute, obtuse or rounded, apex rounded-emarginate, finely pubescent, glabrescent, rather glaucous below, shiny above. Inflorescence an axillary, unbranched raceme, 15-30 cm long; bracts linear, 10-12 mm long, persisting until flowers open; pedicel 1.7-4 m long; calyx deeply 5-lobed, lobes ovate, 10-15 mm x 5-6 mm, densely velvety outside, glabrous inside; petals 5, obovate, 15-25 mm x 10-12 mm, spreading, yellow, hairy towards the base inside; stamens 10, free, filaments 10-15 mm long, woolly at base, anthers dorsifixed; ovary sessile, 5 mm long, hairy, 4-8-ovuled, style filiform, 12 mm long. Pod elliptical, sharp-pointed, 10-15 cm x 2-4 cm, flat, with a wing-like extension 4-5 mm broad on each suture, dull-brown when ripe, later blackish, 4-8-seeded, indehiscent, often hanging in bunches below the leaves. Seed flattened oblongoid, 10-12 mm x 5 mm, transversely positioned. Seedling with epigeal germination; hypocotyl 4-6 cm long; cotyledons stalked, 3-nerved, glabrous. P. dasyrhachis (often erroneously spelled 'dasyrrhachis') is related to P. pterocarpum (DC.) Backer ex K. Heyne, an important source of 'soga' dye. P. dasyrhachis can be distinguished by its crown that is uneven and not umbrella-shaped, its branched stipules, and its thick, reddish tomentum. The two species have occasionally been confounded in the literature. In northern Vietnam, a form of P. dasyrhachis occurs with unbranched stipules and early falling bracts, named var. tonkinense (Pierre) K. & S.S. Larsen.

In Lampung (Indonesia), flowering takes place during the dry season (September-October) and fruits ripen 1 year later. In Indo-China, flowering is from February to April, while new leaves are formed and fruits ripen from May to November. Seed germinates in abundance after a bush fire.

Mainly found on ultisols.

P. dasyrhachis is found in secondary, deciduous or evergreen forest. Due to its relatively deep rooting system, it is drought tolerant. Its hairiness and fairly thick bark have been associated with its tolerance of fire.

It is found in Thailand, Indo-China, Peninsular Malaysia, Sumatera and Borneo. It is also cultivated in many other tropical regions, e.g. in Java.

P. dasyrhachis is propagated by seed or cuttings.

Husbandry: It has been tested as a tree in alley-cropping systems. When unpruned, it provides a rather dense shade to control weeds during fallow periods, and can be managed in hedges without too much shading of inter-row crops. Because its growth rate is slower than that of Leucaena Leucocephala (Lamk) de Wit and Gliricidia sepium (Jacq.) Kunth ex Walp., it requires less frequent pruning. Upon pruning, trees resprout abundantly and form a dense hedge.

Pests: Few insects have been recorded as damaging the leaves, whereas large stem-boring insects attack older trees.

The weight of 1000 seeds is about 37 g.

Erosion control: The slow rate of decomposition of the leaves reduce erosion. Reclamation: Its use in the reclamation of Imperata cylindrica (L.) Raeuschel grasslands is being tested; in Indonesia and Malaysia, young trees planted in tall Imperata grasland and left untended after planting remained alive, but grew slowly. Shade or shelter: In the first half of the 20th century, P. dasyrhachis was used as a shade tree mainly in coffee in Java. In central Thailand it is maintained after bush fallow as a shade tree for fruit trees and for its role in soil improvement. Other services: The slow rate of decomposition of the leaves is also contributes to the suppresion of weeds. Seeds of Imperata cylindrica hardly germinate in soil covered by the leaves.

Fuel: It is suitable as firewood. Medicine: The bark is used in an infusion for coughs. Timber: The red-yellow wood is locally used for planks in house-building, but is of little market value.