Horsfieldia borneensis W.J.deWilde, Gard. Bull. Sing. 39 (1986)

Diagnostics
Mid-canopy tree up to 37 m tall and 65 cm dbh. Stem with red sap. Stipules absent. Leaves alternate, simple, penni-veined, glabrous to hairy. Flowers ca. 2 mm diameter, yellow-pink-brownish, placed in panicles. Fruits ca. 46 mm long, green-yellow-brown, fleshy, glabrous, dehiscent capsules. Seeds with entire orange aril.

Description
Tree 10-37 m tall. Twigs subterete, (1.5-)2-4(-10) mm diameter, sometimes blackish, early to rather late glabrescent, hairs rusty, 0.2-0.4 mm; bark finely striate, not distinctly lenticellate, sometimes finely cracking or slightly flaking. Leaves chartaceous to thinly coriaceous, elliptic-oblong to oblong-lanceolate, 7-18 by 2-6 cm, base (short-)attenuate, apex acute to (short-)acuminate; upper surface drying dull olivaceous to (partially) blackish brown, glabrous, lower surface drying pale brown to chocolate, glabrescent, hairs densely branched dendroid 0.3-0.4 mm (especially on midrib); dots present and obvious; midrib slightly raised above, (late) glabrescent; nerves 10-16 pairs, slender above, flat or sunken (slightly raised only close to the midrib) or in thinner-leaved specimens slightly raised, glabrous, lines of interarching +/- regularly shaped, not distinct; venation hardly or not visible on both surfaces; petiole 12-25 by 1.5-2.5 mm, sometimes late glabrescent; leaf bud 10-17 by 2-4 mm, with dense hairs 0.3 mm long. Inflorescences behind the leaves, with dense short-woolly rusty hairs up to 0.7 mm long; in male: fairly large, many-flowered, about 4 times branched, (8-)13-20 by (5-)10-18 cm, peduncle 1.5-3.5 cm long; in female: 8-10(-13) by 4-5 cm, less branched; bracts elliptic to elliptic-oblong, pubescent as the inflorescences, 1.5-5 mm long, caducous; flowers (male) in loose clusters of 2-6, glabrous; perianth 3-lobed, pedicel distinctly articulated. Male flowers: pedicel 1-1.5 mm; buds subglobose to broadly ellipsoid or broadly obovoid, 1.3-1.8 by 1.2-1.7 mm, cleft c. 1/3 (to nearly 1/2), not collapsing on drying, lobes 0.2-0.3 mm thick; androecium broadly ellipsoid to subglobose, 0.7-1.2 by 0.6- 1.3 mm, the apex broadly rounded, slightly impressed in the centre with cavity to c. 1/4, base rounded, in cross section circular: thecae 16-20, almost completely sessile and mutually closely appressed, at apex incurved over the cavity, free apices about none; column broad; androphore narrow, at most 0.1 mm long. Female flowers: pedicel thickish, glabrous, 1-1.5 mm long, distinctly articulated; buds subglobose or broadly ellipsoid, 3-3.5 by 3 mm, glabrous, cleft c. 1/3; ovary subglobose to broadly ovoid-ellipsoid, 2(-2.5) by 2 mm, glabrous, stigma 2-lobed, 0.2 mm high, descending 1.5 mm down the ovary. Fruits 1-7 per infructescence, ovoid, 4-6 by 3-4.5 cm, glabrous, somewhat laterally flattened and slightly flanged, apex and base rounded, drying brown and often with a glaucous tinge, smooth; pericarp 10-15 mm thick; fruiting pedicel stout, 4-6 mm long; perianth not persistent. [from Flora Malesiana]

Ecology
In undisturbed mixed dipterocarp and swamp forests up to 400 m altitude. Mostly on ridges, but also on alluvial sites. On sandy to clay soils.

Uses
The fruits are edible.

Distribution
Borneo.

Local names
Borneo: Buah kalop, Dara-dara, Darah-darah, Koompang, Kumpang, Kumpang balau, Lala hutan.