Author: (van Steenis) Steyaert
Morphological description
Large trees , up to 45 m high and 90 cm dbh; twigs light to greyish brown, lenticellate, hairy when young, soon glabrescent.
Leaves unifoliolate; petiole (0.5-)1-3 mm long only, petiolule as long as the petiole, glabrescent. Leaflets ovate to ovate-oblong or elliptic, 6.5-16 by 3.5-7 cm, coriaceous; apex bluntly acuminate, often folded when dried; base rounded to cuneate; surfaces concolorous, above often shiny, glabrous, beneath dull, glabrescent; nerves (5-)6-8(-9) pairs, the upper ones sharply arcuating towards the apex, reticulation distinct (procerum Dialium lv/inf/podFM31).
Inflorescence : Panicles axillary or (especially in side branches) terminal, sometimes in fascicles, rachis (6-)9-15(-16) cm; pedicels 2-4 mm long.
Flowers: (procerum Dialium fl parts FM31)Sepals 3, elliptic, 3-4 mm long, minutely hairy inside. Stamens 6; filaments 0.5-1 mm long; anthers linear, c. 2.5 mm long, glabrous or hairy on both sides of the connective. Ovary 1.5-2 mm long; style 0.5-1 mm, slightly recurved at apex.
Fruits ovoid, c. 4(-5) by 2.5 cm, slightly compressed, with distinct sulcate sutures, usually acute to cuneate at base, beaked or apiculate at apex; exocarp blackish, hairs easily detached and glabrescent.
Seeds reniform, c. 1.5 by 1 cm, testa chocolate brown, shiny.
Distribution
Malesia: Peninsular Malaysia, Sumatra, Borneo (Sarawak, Brunei).
Habitat
Primary and old secondary forest, sometimes inundated, altitude 15-560 m.
Ecology
Flowering from June to March; fruiting from January to April.
Notes
1. This is a homogenous species except in the size of the leaves.
2. The species is very close to Dialium kunstleri , especially its var. trifoliolatum .