Macaranga umbrosa S.J.Davies, Harvard Pap. Bot. 6: 422 (2001)

Name meaning 'providing shade or shade loving' referring to the preferred habitat of the species.

Macaranga kingii var. platyphylla Airy Shaw

Small trees up to ca. 15 m tall and 20 cm dbh, reproductive from 4 m tall and 2.5 cm dbh. Twigs hollow, ant inhabited, glabrous, with small ant openings (ca. 1 mm diameter). Stipules ovate to triangular, semi-persistent, recurved, not surrounding the twigs completely, 20-27 mm long by 9-14 mm wide. Petioles glabrous, up to ca. 53 cm long. Leaves alternate, peltate, usually shallowly 3-lobed (cusped), sometimes not lobed, 51-56 cm long by 30-40 cm wide, length/width-ratio 1.4-1.7; secondary veins 12-16, ending in the margin; central lobes 23-24 cm long by 22-32 cm wide, lateral lobes 1.5-4 cm long; leaf base broadly rounded, peltate margin length 7.8-11 cm; leaf margin with glands; leaf upper surface glabrous; leaf lower surface glabrous, not gland dotted. Staminate inflorescences branched; flowers clustered per bracteole; bracteoles with entire margins. Pistillate inflorescences branched; fruits 10-15 mm wide, 4-5(-6)-locular, with two glandular patches on each carpel wall, placed on lengthwise, slightly raised ridges.

Small slender glabrous tree to 15 m tall, flowering from c. 3 m; twigs 8-15(-18) mm in diam.r, glabrous, not glaucous, hollow, housing ants. Stipules narrowly ovate, 15-27 by 8-13 mm, with a finely acuminate apex, recurved with the margins revolute appearing horn-like and appressed to the stem, glabrous, the pair not completely encircling the twig, succulent, producing food-bodies on abaxial surface, up to 6-8 pairs present on the shoots. Leaves: petioles terete, 15-50 cm long, stout, up to 9 mm in diam., not glaucous, glabrous; blades ovate to broadly ovate, often huge, 20-60 by 14-35 cm, dark shiny green on both surfaces and appearing slightly bullate above, entire or usually with short lateral cusps, very deeply peltate to 4-11 cm, base broadly rounded, margin entire, with small protruding nectaries, apices acute, adaxial surface glabrous, abaxial surface glabrous or sometimes with extremely minute silvery crisped hairs on the main veins, not glaucous; 1st degree venation palmate with 7-8 prominent veins, 2nd degree venation looping near the leaf margins and forming a subprominent marginal collecting vein and sometimes ending at the margin in small flattened nectaries, 3rd degree venation scalariform, 4th degree venation loosely scalariform, finer veins loosely reticulate; young leaves dark red below, glabrous or scattered with minute ferrugineus hairs. Staminate inflorescences paniculate, erect, 6-15 by c. 6 cm, glabrous, up to 3 axis orders, main axis flattened, first pair of secondary branches +/- opposite with or without accessory branches; bracts ovate, 8-15 by 5-10 mm, persistent, margin entire, apex acute, glabrous; flower clusters with 1-5 flowers, spirally arranged and crowded towards the ends of inflorescence branches; bracteoles ovate, 4-6 by 3-4 mm, thin and delicate, enclosing flower clusters, margin entire, apex acuminate, glabrous, scattered with yellow granular glands. Staminate flowers c. 1.5 mm long, pedicellate; sepals free, with scattered minute red-brown hairs and yellow glands, membranous; stamens 4-7; anthers 4-locular. Pistillate inflorescences particulate, erect, 3-12 cm, stout, glabrous, not glaucous, to 2 axis orders, secondary branches +/- opposite, bracts narrowly ovate, 8-10 by 3-5 mm, glabrous, with scattered yellow glands, caducous. Pistillate flowers 8-15 mm, solitary in bract axils; calyx urceolate, 4-6 mm long, not glaucous, glabrous or with scattered ferrugineus hairs near the base, persistent, splitting irregularly as the ovary expands; ovary 4-5- (rarely 6)-carpellate, 4-6 mm long; styles 4-9 mm long; styles fused at base, free and spreading from c. 1/2 of the length, persisting to form a prominent 6-8 mm long crown at fruit apex; stigma shallowly dissected. Fruits subglobose, 9-12 by 10-15 mm, pale pink to bright red, pedicellate, two discrete glandular patches on each carpel wall developing into narrow ridges raised to 1-2 mm, covered in dark, sticky exudate; pedicel 10-30 mm long, glabrous, not glaucous. Seeds subtriangular- ovoid, 5.5-6.5 mm in diam., black, with shallow narrow grooves and a small cruciform scar, encased in a fleshy bright orange-red aril. [from Flora Malesiana]

Collected up to ca. 600 m altitude. A shade-tolerant forest understorey species, mainly found in primary forests, but also present in closed secondary forests.

Endemic for Borneo, where it has been collected in Sarawak, Brunei, Sabah and Central Kalimantan.