Dipterocarpus humeratus Sloot., Bull. Jard. Bot. Btzg III, 8 (1927)

Synonyms
Dipterocarpus gibbosus Sloot.
Dipterocarpus retusus (non Bl.) Ridl.
Dipterocarpus ursinus Sloot.
Dipterocarpus validus (non Bl.) Brandis

Diagnostics
Emergent tree up to 59 m tall and 113 cm dbh. Stem with resin. Stipules up to ca. 100 mm long. Leaves alternate, simple, penni-veined, glabrous, lamina folded between secondary veins. Flowers ca. 30 mm in diameter, greenish-white, placed in racemes. Fruits ca. 30 mm long, green-red, with two ca. 185 mm long wings placed on top of the nut, wind dispersed.

Description
Young twig, petiole, midrib and nerves beneath persistently shortly cream pubescent; leaf bud and stipule outside long fulvous tomentose, the hair tufts becoming separated widely and partially caducous on the expanding stipule. Twig 1-1.2 cm diamater apically, becoming uneven and thinly flaky, terete. Bud to 5 by 1.5 cm, narrowly conical, obtuse. Stipule to 10 by 2 cm, narrowly lanceolate, obtuse. Leaves 20-38 by 12-23 cm, broadly ovate; base obtuse; apex obtuse to shortly acuminate; nerves c. 20 pairs, prominent, well spaced, at 45-60 degrees; petiole 4-6 cm long, stout, prominently geniculate. Raceme to 21 cm long, terminal or axillary, terete or slightly compressed, long golden-brown caducous tomentose at base, more shortly so distally; usually unbranched. Flowers remote, distichous; bud to 5 by 2 cm, large. Calyx and corolla typical, calyx glabrous. Stamens c. 40, longer than style; filaments c. half as long as anthers; anthers linear, tapering; appendage to connective as long as anther or slightly longer, slender. Ovary ovoid-conical, shortly pubescent; stylopodium 2-3 times as long as ovary, shortly pubescent the apex excepted. Fruit subsessile. Calyx tube to 4 by 3.5 cm, globose, glabrous, with 5 obtuse tubercles in the apical half, terminating abruptly at the c. 2.5 cm neck; 2 longer calyx lobes to 18 by 5 cm, oblong, obtuse, tapering abruptly at the to 1.2 cm broad revolute base, untwisted; 3 shorter lobes to 1.5 cm long and broad, broadly ovate, base subcordate, apex obtuse, revolute with the 2 halves back to back. [from Flora Malesiana]

Ecology
In undisturbed mixed dipterocarp forests up to 600 m altitude. On hillsides and ridges with sandy to clayey soils.

Uses
Timber is commercially harvested.

Distribution
Sumatra, Borneo.

Local names
Borneo: Bajan, Keruing kerupok, Keruing kipas, Tempehes, Tempudau.
Malaysia: Keruing kerukup, Keruing latek bukit.