Knema percoriacea J.Sinclair, Gard. Bull. Sing. 18 (1961)

Latin for 'very tough or leathery', referring to the leaves.

Diagnostics
Mid-canopy tree up to 33 m tall and 49 cm dbh. Bark of trunk rather smooth, fissured, scaly, or flaking; living bark inside red-brown or pinkish; wood usually white, sometimes reddish, or red brown. Leaves glossy dark green with whitish midrib above, glaucous with yellowish green midrib beneath. Flowers with yellow to rusty indumentum. Fruits ellipsoid or round, with yellowish or rusty indumentum.

Description
Tree 5-25(-33) m. Twigs sometimes faintly angled, 3-6 mm diameter, at first with pale to dark brown hairs 0.5-2 mm long, late glabrescent; bark smooth or striate, then usually slightly to distincly longitudinally cracking, and flaking. Leaves chartaceous or coriaceous, (oblong- )lanceolate, 12-40 by 2.5-9(-15) cm, apex subobtuse to acute(-acuminate), base attenuate to rounded, drying olivaceous or brown above, lower surface glabrous, not or but little papillate, with scattered hair scars (lens!); dots absent; midrib much raised above; nerves 15-25 pairs, raised above; venation distinct; petiole sometimes +/- pulvinate, late glabrescent, 7-25 by 3-8 mm. Inflorescences: peduncle up to 2 mm long, brachyblast simple, warted, or 2-furcate, up to 15 mm long; in male 10-20-flowered. female up to 15-flowered; flowers with light brown or dark brown hairs 0.5-2 mm long, sometimes partly deciduous; perianth 3-lobed, red inside. Male flowers: pedicel 3-4.5 mm long, bracteole persistent, at or above the middle; buds depressed (globose-)obovoid, (3.5-) 4-5.5 by (3.5-)4-5.5 mm, cleft 2/3-3/4, lobes 0.5(-1) mm thick; staminal disc circular or subtriangular, flat, 2-2.5 mm diameter; anthers 10-18, shortly stiped or subsessile, half-erect or curved upward, 0.3-1 mm long, not or but little touching; androphore 1-1.5 mm, finely striate. Female flowers: pedicel 2-4 mm long, bracteole subapical; buds ovoid or ellipsoid, 6.5-8(-9) by 5-7 mm, cleft slightly over halfway, lobes 0.5-0.7 mm thick; ovary subglobose, 3.5-4 mm diameter, stigma sessile. 2-lobed and each lobe again 8-10-lobulate or serrate. Fruits 1 or 2 per infructescence. (broadly) ellipsoid, sometimes slightly flattened, 3-4.5(-5) by 2.5-3.5(-4.5) cm, with rusty hairs 1-2 mm long; dry pericarp 4 mm thick; fruiting pedicel 2-3 mm long. [from Flora Malesiana]

Ecology
In undisturbed mixed dipterocarp and keranga forests up to 700 m altitude. Usually on hillsides and ridges, rarely on alluvial sites. On sandy soils, sometimes also on clay soils.

Distribution
Borneo.

Local names
Borneo: Kumpang, Mandarahan, Pendarahan.