Dipterocarpus sublamellatus Foxw., Malayan Forest Rec. 10: 92 (1932)

Diagnostics
Large emergent trees. Stipules hairy. Leaves alternate, tough, glabrous, very clear venation, wavy margin. Flowers few per inflorescence, large. Fruits generally one per inflorescence, up to 12 cm long (two wings included), reddish-green, with wavy plates along the nut.

Description
Large emergent trees with buttresses. Leaf bud and stipule outside (glabrous within) densely long pale fulvous hirsute, rarely glabrous, leaf nervation beneath sparsely caducously so, otherwise glabrous. Twig to 3 mm diameter towards the apex, much branched, slender, dark, lustrous, smooth: stipule scars pale, prominent. Bud to 12 by 8 mm, ellipsoid-ovoid, subacute. Stipule to 40 by 8 mm, lorate, acute. Leaves 5-15 by 3.5-8 cm, ovate to elliptic (immature), coriaceous persistently prominently plicate; base broadly cuneate; acumen short, slender, to 1 cm long in young trees; nerves 8-12 pairs, prominent beneath, ascending at 35-55'; tertiary nerves very slender, densely scalariform; petiole c. 1.5(-3) cm long, slender, geniculate, drying black or pruinose. Inflorescence unknown. Flower bud to 3.5 by 1 cm. Calyx and corolla typical: calyx glabrous. Stamens c. 24, as long as style at anthesis; filaments lorate, slender, compressed, somewhat longer than anther: anther linear, tapering into the acicular appendage; appendage c. 0.5 times length of anther. Ovary ovoid, pubescent; style columnar, pubescent except in the apical 1/3. Fruit calyx tube to 3 by 3 cm, globose, bearing 5, to 1.5 cm wide, incrassate undulate wings; wings tapering distally, auriculate at base; 2 longer calyx lobes to 12 by 3 cm, lorate, obtuse, c. 6 mm wide at the somewhat revolute base; 3 shorter calyx lobes to 5 by 7 mm, suborbicular, revolute. [from Flora Malesiana]

Ecology
Undulating land and low hills to 500 m. Locally common, especially in moist places.

Uses
Timber is used.

Distribution
Peninsular Malaysia, Sumatra, Borneo.

Local names
Malaysia: Keruing kerut. keruing padi, keruing sugi.
Sumatra: Lagan batu, Lagan boeih, masibuk.