Macaranga rostrata Heine, Repert. Spec. Nov. Regni Veg. 54: 233 (1951)
Name meaning 'beaked'.
Synonyms
Diagnostics
Small trees up to ca. 20 m tall and 30 cm dbh, reproductive from 7 m tall and 4 cm dbh. Twigs solid,
glabrous to hairy. Stipules ovate, semi-persistent, erect to spreading, not surrounding the twigs
completely, 6-10 mm long by 3-5 mm wide. Petioles glabrous to hairy, up to ca. 12 cm long. Leaves
alternate, ovate, peltate or not, 9-18 cm long by 4.5-11 cm wide, length/width-ratio 1.18-2.07;
secondary veins 8-10, usually ending in the margin, sometimes looping; leaf base rounded to cordate
(also when peltate), peltate margin length (when present) 0.1-1.2 cm; leaf margin with conspicuous
glands; leaf upper surface glabrous, with 2-6 basal nectary glands on basal veins, some distance
from petiole insertion; leaf lower surface hairy, not or only sparsely gland dotted. Staminate
inflorescences branched; flowers clustered per bracteole; bracteoles with entire margins. Pistillate
inflorescences branched; fruits 9-10 mm wide, 4(-5)-locular, one glandular patch on each carpel wall
developing into very long horn-like appendages.
Description
Submontane tree to 20 m tall; twigs slender, 3-5 mm in diam., terete, glabrous or finely pubescent
with short silvery hairs, not glaucous, solid, not housing ants. Stipules ovate-elliptic, 5-10 by
3-5 mm, erect and spreading from the twig and sometimes slightly recurved when dry, abaxial surface
finely pubescent along the midrib and towards the base, adaxial surface mostly glabrous, the pair
not completely encircling the twig, leathery but not succulent, 1-4 pairs present on shoots. Leaves:
petioles terete, 3-12 cm long, finely pubescent with short silvery or golden hairs, rarely almost
glabrous; blades ovate-elliptic, broadest near the base, 9-20 by 4-10(-12) cm, not or only shallowly
peltate with the petiole insertion less than 15 mm from the basal leaf margin, base rounded or slightly
cordate when not peltate, margin entire to almost wavy or serrate, apix acute to narrowly acuminate,
adaxial surface glabrous or rarely with minute scattered hairs along the veins and with 2-4 round or
oval c. 1 mm diameter flat nectaries adjacent to the basal leaf margin near the petiole insertion,
abaxial surface densely pubescent along all veins or rarely sparsely pubescent, not glaucous; 1st
degree venation palmate with 5-7 prominent veins, 2nd degree veins scalariform looping near the leaf
margins and terminating in small protruding flattened nectaries, 3rd degree veins scalariform; young
leaves red-brown, densely pubescent along the veins, the very youngest leaf bud densely covered in
erect pointed silvery or golden hairs. Staminate inflorescences slender, green when fresh, drying
blackish, paniculate, erect, 4-15 by 1-6 cm, glabrous or sometimes scattered with silvery hairs on
the basal axes and minute ferrugineus hairs on the distal axes, to 3(-4) axis orders, main basal
axis short, flattened, first pair of secondary branches +/- opposite and usually with accessory
branches; bracts elliptic, 5-12 by 3-6 mm, margin entire, apex acute, mostly glabrous or margin and
adaxial surface scattered with minute ferrugineus hairs, caducous; flower clusters with 15-25
flowers, spirally arranged and evenly spaced; bracteoles broadly rounded, 2-4 by 3-5 mm, cupulate,
enclosing flower clusters, margin entire, apex shortly acute, adaxial surface densely covered with
minute ferrugineus hairs particularly towards the base, abaxial surface scattered with ferrugineus
hairs and yellow granular glands. Staminate flowers c. 1 mm long, sessile; sepals fused, splitting
to c. 1/5, apex densely covered in minute red-brown hairs; stamens 1; anthers 3-locular. Pistillate
inflorescences erect, shortly paniculate, 3-7 by 1-3 cm, stout, 1-2 axis orders, secondary branches
+/- opposite, green when fresh and drying black, mostly glabrous but main basal axis usually with
scattered erect silvery hairs; bracts caducous, not seen. Pistillate flowers 5-6 mm long, solitary;
calyx c. 3 mm long, urceolate, glabrous, persistent, splitting irregularly as ovary expands; ovary
4(-5)-carpellate, 3-4 mm long; styles 2-3 mm long, fused at base, free and spreading from c. 1/3 of
length, persisting to form a prominent 3-4 mm long crown at fruit apex; stigma not dissected. Fruits
subglobose, 6-8 (excluding horns) by 9-10 mm, sessile, one discrete glandular patch on each carpel
wall developing into a very long and slender horn-like process 7-15 mm long, covered in sticky
yellow-green exudate. Seeds subtriangular-ovoid, c. 4 mm in diam., black, with shallow coarse
grooves and a small cruciform scar, encased in a fleshy aril, aril color not seen. [from Flora Malesiana]
Ecology
Usually in gaps or along forest edges up to an elevation of 2300 m.
Distribution
Borneo.
Local names
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