Macaranga pruinosa (Miq.) Mull.Arg., in DC. Prodr. 15, 2 (1866)

Synonyms
Macaranga formicarum Pax & K.Hoffm.
Macaranga maingayi Hook.f.
Mallotus maingayi Durand & Jacks. [Illegitimate]
Mappa pruinosa Miq. Tanarius maingayi (Hook.f.) Kuntze
Tanarius pruinosus (Miq.) Kuntze

Diagnostics
Sub-canopy tree up to 30 m tall and 40 cm dbh. Twigs solid. Stipules curved upwards, ca. 9 mm long. Leaves alternate, simple, 3-lobed, peltate, palmately-veined. Flowers ca. 0.5 mm diameter, green-yellowish, placed in groups within bracts which are placed in long panicles. Fruits ca. 5 mm diameter, green-yellowish, 2-lobed, dehiscent capsules, seeds with pink aril.

Description
Peat swamp tree to 25-30 m tall and 30-40 cm dbh, flowering smaller; twigs 5-12 mm in diam., terete, either glabrous and densely glaucous or densely covered in short erect silvery hairs and not glaucous, sometimes hollow and ant-inhabited. Bark pale grey to white, hoop-marked, smooth. Stipules rounded, 8-15 by 8-15 mm, erect, usually saccate, glabrous or finely tomentose, the pair not completely encircling the twig, coriaceous, sometimes producing food-bodies on the adaxial surface, usually 3-5 pairs persistent on the shoots. Leaves: petioles terete, 10-25 cm long, sometimes slightly glaucous towards the base, either mostly glabrous with scattered ferrugineus hairs towards the leaf insertion or densely silvery pubescent; blades very broadly ovate to rounded, 8-25 by 8-27 cm, evenly trilobed with the central lobe slightly larger than laterals, dissected to c. 1/3-1/2, deeply peltate to 1.5-4 cm, base broadly rounded, sometimes slightly cordate, margin +/- entire, apices acute or shortly acuminate, adaxial surface mostly glabrous but moderately to densely ferrugineus pubescent along the veins particularly near the petiole insertion, abaxial surface densely pubescent with fine erect silvery hairs and minute ferrugineus hairs, sometimes the silvery hairs absent, minutely furfuraceous; 1st degree venation palmate with 5-9 prominent veins, 2nd degree venation scalariform looping and terminating at the margins in prominent conical nectaries, 3rd degree venation densely scalariform, 4th degree venation weakly scalariform, finest nerves densely reticulate; young leaves adaxial surface densely ferrugineus tomentose, abaxial surface covered in fine erect silvery hairs or a silvery tomentum, the margin often with erect silvery hairs. Staminate inflorescences paniculate, erect, 6-18 by 4-10 cm, all axes densely minutely silvery or golden ferrugineus pubescent, the basal axis sometimes +/- glabrous, 3-4 axis orders, main axis short and terete or slightly flattened, first pair of secondary branches alternate without accessory branches; bracts narrowly ovate, 2-4 by 2-3 mm, margin entire, apex acute, glabrous or scattered with ferrugineus hairs towards the base and on the margins, persistent; flower clusters with 6-15 flowers, spirally arranged on the inflorescence branches; bracteoles ovate to narrowly ovate, 3-5 by 2-3 mm, often with quite straight sides to almost strap-like, margin shallowly irregularly dentate with 4-8 small unequal teeth, apex rounded to broadly acute, veins slightly raised on the abaxial surface, both surfaces densely covered with fine silvery and ferrugineus hairs. Staminate flowers c. 0.7 mm long, shortly pedicellate; sepals 3, free, densely ferrugineus pubescent; stamens 2-3; anthers 4-locular. Pistillate inflorescences paniculate, erect, 5-18 by 2-8 cm, sparsely branched, densely ferrugineus pubescent throughout, the hairs slightly less dense on basal axes, 2-3 axis orders; bracts ovate, 3-4 mm long, margin entire, glabrous or with scattered hairs on the margins, caducous. Pistillate flowers c. 1.5 mm long; calyx urceolate, densely minutely ferrugineus or golden pubescent; ovary 2-carpellate; styles c. 1 mm long, free, persistent; stigma very shortly dissected. Fruits c. 5 by 5-6 mm, bilocular, locules subglobose, pedicellate, evenly covered in glandular yellow sticky exudate, without processes; pedicel 4-6 mm long, finely ferrugineus hairy. Seeds c. 3 mm in diam., lenticular, black, with shallow grooves, encased in a fleshy pale purple aril. [from Flora Malesiana]

Ecology
Often gregarious in (peat)-swamp forests up to 100 m altitude. Also found in degraded mixed dipterocarp and swamp forests, often along rivers or road sides. A large early successional tree of lowland peat swamp forest. It often forms huge monospecific stands in degraded areas. Enormous areas, for example, between KLIA at Sepang and the city of Kuala Lumpur in Peninsular Malaysia, and between Kuching and Kota Samarahan in Sarawak, are completely dominated by this species. The distinctive uniform canopies of M. pruinosa stands can be seen from far away. Little is known about the seedling ecology of this species, but it may prove useful for restoring and limiting erosion in degraded peat swamp areas.

Distribution
Peninsular Thailand, Peninsular Malaysia, Sumatra, Borneo.

Local names
Borneo: Mahang laki, Mahang prempuan, Mahang puran, Sabang.