Tree 7-30 m. Twigs 2.5-4 mm diameter, early glabrescent, hairs grey-brown, up to 0.1 mm long; bark finely to coarsely striate, not flaking; lenticels conspicuous or inconspicuous. Leaves membranous, (elliptic-)oblong, 9-21 by 3-9 cm, base attenuate, apex acute-acuminate; upper surface drying dull olivaceous or dark brown, lower surface glabrous; scattered dots (0.1 mm diameter) present; midrib ± flat above; nerves 11-16 pairs, thin, flat above, lines of interarching not distinct; venation lax, hardly visible on both surfaces; petiole 10-17 by 1.5-3 mm, glabrous; leaf bud 8-12 by 1.5-2 mm, with dense grey-brown hairs up to 0.1 mm long. Inflorescences with sparse hairs up to 0.1 mm, or glabrescent; in male: about 3 times branched, rather many-flowered, 4-10 by 2-8 cm, peduncle 0.5-2 cm long; in female: about twice branched, 3-6 by 1.5-4 cm, fewer-flowered than in male; bracts ± oblong, 2-4 mm, short-pubescent, caducous; flowers in male in loose clusters of 2-5, glabrous, perianth 3-or 4-lobed, pedicel not articulated. Male flowers: pedicel 1-4 mm, slender; buds depressed-globose, 1.4-2 by 1.6-2.2 mm, cleft 3/4-4/5, lobes 0.2-0.3 mm thick; androecium depressed-globose to depressed broadly ovoid, 0.6-0.7 by 1-1.5 mm, nearly circular in cross section (Plate 3: 90); thecae 14-18, completely sessile (free apices up to 0.1 mm), the apices of anthers concealing the apical hollow, column broad with narrow hollow up to 0.2 mm deep, in Sumatra up to 0.4 mm deep; androphore narrow, 0.1-0.2 mm long. Female flowers: pedicel 1-2 mm long; buds ellipsoid, 2.8-3.5 by 2.5-3 mm, cleft c. 1/2; ovary broadly ovoid, 1.5-2 by 1.3-2 mm, glabrous, stigma irregularly 2-lipped, 0.2-0.3 mm high. Fruits 1-3 per infructescence, (broadly) ellipsoid, glabrous, 4.5-8 by 3-4.5 cm, drying blackish brown, without or with few small warts; pericarp 10-20 mm thick; fruiting pedicel 4-6 mm long; perianth not persistent.
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