Dialium platysepalum

Author: Baker

Morphological description
Trees , up to 45 m and 90-120 cmin diameter; twigs greyish-brown to rusty-brown, young parts brownish hairy.

Leaves imparipinnate, incl. petiole (10-)15-24(-28) cm long; petiolules 2-4.5 mm. (platysepalum Dial lf CToS35 )Leaflets (5-)7-11(-15) pairs, oblong-elliptic to -lanceolate, (5-)6-8(-15) by (1.5-)2-4(-7) cm, (sub)coriaceous, hairy, sometimes late glabrescent; apex abruptly to long acuminate, acumen up to 2 cm; base rounded to cuneate; upper surface dark brown when dry, lower surface chocolate brown to rusty brown; nerves 10-12(-15) pairs, distinct on both surfaces, sometimes obscured below by thick, golden hairs.

Inflorescence : Panicles terminal, the lower branches usually subtended by leaves, rachis 10-15(-30) cm, usually rusty brown; pedicels (2-)2.5-4(-7) mm.

Flower buds up to 7.5 mm long. Sepals 5, triangular, up to 6 by 4 mm, minutely hairy inside. Stamens 2; filaments 1-2.5 mm long; anthers with both slits drawn towards the abaxial side, forming a v-channel on the abaxial side of the connective, 3-4(-5) mm long, hairy. Ovary 2-3.5 mm long; style sharply recurved at top, up to c. 3 mm long, usually sparsely hairy on lower half.

Fruits subglobose to obovoid, sometimes slightly compressed. (1.5-)2-2.5(-3) cm long, sometimes up to 2 mm stipitate; pericarp firm, exocarp densely brown velvety, persistent (platysepalum Dia fr CToS 35 ).

Seeds 1(-2), roundish to reniform, 3-13 by 9 mm, testa lightbrown to blackish, shiny.

Malesia: Peninsular Malaysia, Singapore, Sumatra, Borneo.

Usually in low-lying areas and hills, up to c. 500 m altitude. Also in freshwater swamp forest.

Flowers throughout the year, with peaks in December-March and May-September, fruits heaviest in July-October.

1. This species is distinct from all other species of Dialium . Mature flower buds as well as anthers are the largest in the genus. The base of the flower bud is usually incurved appearing distinctly zygomorphic, and the receptacle is deeply concave with filaments and ovary inserted excentrically on opposite sides.
2. By the size of the leaflets and the colour and quality of the indumentum on their undersurface the species can be segregated into more or less discrete 'groups'. The 'maingayi ' group has a rather whitish to slightly golden indumentum underneath, the nerves are not very distinct. The 'platysepalum ' group is the most common group, but not easily separated from the previous one; the leaves are often tinged golden underneath. Leaves in the 'wallichii ' group are slightly golden or light yellow beneath but the blades are smaller, not more than 7 by 2 cm. In the 'kingii ' group leaves are slightly larger than in 'wallichii ', the under surface is golden to chocolate brown, the nerves are prominent. In the 'riste ' group the chocolate brown leaves are still larger and the nerves much more prominent. The differences between the 'groups' are slight and they form a gradient with intermediate specimens, so they are given no taxonomic and nomenclatural status.