Tree 10-30 m. Leaves chartaceous to thinly coriaceous, elliptic-oblong to oblong-lanceolate, 7-18 by 2-6 cm, base (short-)attenuate, apex acute to (short-)acuminate; Inflorescences behind the leaves, with dense short-woolly rusty hairs up to 0.7 mm long; 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;
Asia-Tropical: Borneo present (Sabah present, Sarawak present), E & NE Kalimantan present
Malesia: Borneo (Sarawak, Sabah, E & NE Kalimantan).
1 Horsfieldia borneensis and H. wallichii both have characteristic blackish dots on the lower leaf surface, a dull upper leaf surface with largely sunken nerves, and similar fruits (although the perianth in H. wallichii is persistent). However, H. wallichii, which also occurs in Borneo, is generally stouter and has much larger leaves, often with a persistent indumentum. Above all, it differs in general appearance, shape, and structure of the androecium, and the pedicel which is not articulated. 2 Horsfieldia borneensis, with its dotted lower leaf surface, belongs to a group of species including H. wallichii and H. pulcherrima, while the structure of its androecium links it to species such as H. flocculosa, H. grandis, and H. pulcherrima; compare also H. punctatifolia.