Trigoniastrum hypoleucum Miq., Fl. Ind. Bat. Suppl. (1860)

Latin for 'white underside', referring to the white lower leaf surface.

Isopterys penangiana Wall. ex Benn.

An evergreen, small to medium-sized tree up to 30(-47) m tall; bole usually columnar, up to 50(-60) cm in diameter, sometimes with buttresses up to 1(-2) m high; bark surface smooth, lenticellate, pale greenish-grey to brown, inner bark granular, pale greenish-yellow to yellowish-brown, exuding a yellowish sticky juice which turns reddish upon exposure; crown conical to hemispherical. Stipules small. Leaves alternate, simple, entire, with small glands along the margin and at the top; stipules caducous. Flowers in an axillary or terminal, puberulous panicle, fragrant, zygomorphic; sepals 5, free, unequal; petals 5, free, very unequal, white, one of them saccate at base; stamens 6, united in a tube; ovary superior, 3-locular with 2 pendulous ovules in each cell one of which is aborted in fruit, style simple. Fruit a schizocarp, splitting into 3 flat, winged, 1-seeded samaras. Seedling with epigeal germination; cotyledons emergent, fleshy; hypocotyl elongated; first pair of leaves opposite, subsequent ones alternate, all leaves white puberulous below. [From]

On nutrient-poor to rich soils. T. hypoleucum occurs scattered in a wide range of lowland to submontane, evergreen forest types like peat-swamp, freshwater swamp, kerangas, alluvial and mixed dipterocarp forest. It is sometimes encountered in disturbed forest. Occurring up to 1200 m elevation. In Borneo usually on hillsides with poor ultrabasic to sandy soils.

Timber: The wood of T. hypoleucum has been used for furniture. The poles are used to punt canoes. Ornamental: The tree may be suitable for ornamental purposes. Shade or shelter: The tree may be suitable for shade purposes.

Peninsular Malaysia, Sumatra, Borneo (throughout the island).

Local names
Borneo: Atap, Kikir, Lia, Mangkudor, Mengilas babi, Miapa, Miapa kadazan, Ngilis, Nglumi, Nyalin, Nyalin bintek, Tulang kwe.
Brunei: mengilas babi (Iban).
Indonesian: tinggiran batu (Palembang, Sumatra).
Malay: mata pasak (Peninsular).