Trigonostemon laevigatus Mull.Arg., Flora 47 (1864)

Latin for 'glabrous'.

Trigonostemon anomalus Merr.
Trigonostemon laevigatus var. petiolaris Airy Shaw
Trigonostemon petelotii Merr.

Understorey tree up to 14 m tall and 19 cm dbh. Stipules ca. 1 mm long. Leaves alternate, simple, tripli- to penni-veined, glabrous, petiole ranging from very short to long, basal pair of secondary veins running very close to leaf margin. Flowers ca. 12 mm diameter, bright red, placed on long stalks in compressed racemes. Fruits ca. 14 mm diameter, green-bluish, on long stalk, 3-lobed, dehiscent capsules.

Shrubs or small trees up to 5(-14) m high; branchlets terete, pubescent. Stipules triangular, 1-1.5 mm long. Leaves subopposite; petiole 0.3-1(-1.5) cm long, sparsely hairy, glabrescent, ribbed; blade ovate to obovate, 8.4-15(-23.7) by 3-8(-9.1) cm; thinly chartaceous; base broadly cuneate or obtuse, margin entire, slightly undulate, apex acute to cuspidate, very apex blunt; venation triplinerved, nerves in 7-10 pairs. Inflorescences cymose, axillary, 4-4.5 cm long. Staminate flowers pedicel c. 2 mm long, glabrous; sepals outer 3 smaller, ovate, 1.3-1.5 by 0.8-1, hairy outside; petals ovate, 3-3.2 by 2.5-2.7, yellowish; stamens 3, staminal column very short, c. 0.1 mm long, anthers 0.3-0.4 mm long. Pistillate flowers: pedicel 1.5-2 cm long; sepals oblong, 1.4-1.4 by 0.7-0.9; petals elliptic, 1.5-2 by 1-1.5 mm, yellowish; disc annular; ovary hairy, style c. 0.1 mm long. Fruits: pedicel 3.5-4.5 cm long; capsule globose, axis 6-7 mm long. Seeds trigonous, 6-7 by c. 5 mm. [from Flora Malesiana]

In undisturbed mixed dipterocarp forest up to 1300 m altitude. Usually on hillsides and ridges with sandy to clay soils.

Andaman Islands, Indo-China, Burma, Thailand, Peninsular Malaysia, Sumatra, Borneo, Philippines.

Local names
Borneo: Jingah tulang tiga.