Tree 5-15 m. Leaves membranous or thinly chartaceous, elliptic to oblong-lanceolate, 6.5-16.5 by 3-6.5 cm, base attenuate, apex acute-acuminate; Inflorescences with (sparse) stellate hairs 0.1-0.2 mm long; Fruits 1-3 per infructescence, ellipsoid, base sometimes shortly tapered, 1.7-2 by 1.4-1.5 cm, glabrous, without lenticel-like tubercles;
Asia-Tropical: Borneo present (Brunei present, Sabah present, Sarawak present), Beaufort Hill present, E Kalimantan present, Jesselton present
Malesia: Borneo (Sarawak: 1st Div.; Sabah: Beaufort Hill, Jesselton; Brunei, E Kalimantan).
Horsfieldia tenuifolia is characterized by twigs which are glabrous to the apex, small and slender leaf buds, with hairs only 0.2 mm long, by leaves membranous to thinly coriaceous, not very brittle, drying to a greyish tinge, and the not markedly different colour of upper and lower surfaces, relatively long and slender petioles, and by comparatively small inflorescences and flowers. According to the male flowers the species is close to H. polyspherula. Another closely related species is H. macilenta, also with thin membranous leaves, but with much more pubescent twigs and inflorescences.