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

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

Synonyms
Isopterys penangiana Wall. ex Benn.

Description
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 http://www.worldagroforestry.org]

Ecology
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.

Uses
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.

Distribution
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).