Macaranga hosei King ex Hook.f., Fl. Brit. India 5: 449 (1887)
Species named after 'Charles Hose' [1863-1929?], collector in the service of the Rajah of Sarawak
in the 19th century.
Synonyms
Macaranga pseudopruinosa Pax & K.Hoffm. in Engl.
Diagnostics
Tree up to ca. 30 m tall and 45cm dbh, reproductive from 4 m tall and 5 cm dbh. Twigs starting
out solid, after ant colonization (usually in sapling stage) hollow, glabrous, sometimes glaucous,
with small ant openings (ca. 1 mm diameter). Stipules (broad ovate to) rounded, persistent,
usually perpendicular to the twig, usually (almost) completely surrounding the twig, 9-21 mm long
by 10-20 mm wide. Petioles glabrous, up to ca. 30 cm long. Leaves alternate, usually not peltate,
3-lobed, 10-24 cm long by 14-34 cm wide, length/width-ratio 0.65-0.82; secondary veins 7-18,
ending in the margin; central lobe 4.5-16 cm long by 5.5-12 cm wide, lateral lobes 3.5-13 cm long;
leaf base broadly cordate (usually also when peltate), peltate margin length (when present)
0.3-1.8 cm; leaf margin with glands; leaf upper surface glabrous; leaf lower surface usually
densely hairy (short simple hairs), densely gland dotted. Staminate inflorescences branched;
flowers clustered per bracteole; bracteoles with fimbriate margin; Pistillate inflorescences
branched; fruits 5-6 mm wide, 2-locular, covered with yellow sticky glandular exudates.
Description
Large tree with a bluish-green appearance, to 20-30 m tall and 30-40 cm dbh, although flowering
somewhat smaller; twigs 6-11 mm in diam., terete, glabrous, usually densely glaucous. Bark pale
grey, white or light brown, prominently hoop-marked, smooth or minutely fissured. Stipules 10-15
by 10-15 mm, orbicular surrounding the stem, erect and perpendicular to the stem, many pairs
persistent, coriaceous, not succulent, glabrous, producing food bodies on the adaxial surface.
Leaves: petioles terete, slender, 10-25 cm long, slightly glaucous, glabrous; blades broader than
long to almost rounded, not flat, slightly convex, 8-20 by 10-25 cm, deeply trilobed, dissected
to c. 1/2-3/4, the lateral lobes almost the same size as the central lobe, the lateral lobes
slightly asymmetrical, not peltate or rarely 1-5 mm peltate, base very broadly rounded, strongly
cordate, margin +/- entire with small conical nectaries along the basal margin and usually along
all margins, the distal margin sometimes appearing wavy to dentate, apices acute or shortly
acuminate, 1st degree venation palmate with 5 prominent veins and 2-3 less prominent veins arising
from the petiole insertion, 2nd-3rd veins densely scalariform, 4th venation loosely scalariform,
minor veins usually prominent and finely reticulate; adaxial surface glabrous, abaxial surface
with dense to rarely sparse erect silvery hairs along all veins and densely punctate glandular;
young leaves green, adaxial surface glabrous or with a few minute ferrugineus hairs at the petiole
insertion, abaxial surface densely covered in silvery erect sharp hairs. Staminate inflorescences
erect narrow panicles often extending above the leaves, 20-40 by 10-20 cm, to 4 axis orders, basal
unbranched axis strongly flattened and usually more than 1/2 of the total inflorescence length,
first pair of secondary branches alternate without accessory branches, basal axes glabrous, distal
axes with silvery to ferrugineus pubescence; bracts ovate, 5-7 mm long, margin entire, glabrous,
often persistent; flower clusters with 6-15 flowers, spirally arranged on inflorescence branches;
bracteoles broadly ovate, 4-6 by 3-4 mm, margin irregularly deeply dentate with spreading narrow
unequal teeth, apex broadly acute, both surfaces covered in minute silvery to ferrugineus hairs.
Staminate flowers c. 0.7 mm long, yellow-green, shortly pedicellate; sepals 3, free, densely
pubescent; stamens 2-3; anthers 4-locular. Pistillate inflorescences erect narrow panicles often
extending above the leaves, 15-35 cm long, up to 3 axis orders, basal unbranched axis strongly
flattened and usually more than 1/2 of the total inflorescence length, basal axes glabrous, distal
axes with silvery to ferrugineus pubescence; bracts ovate, 5-10 mm long, margin entire, glabrous,
often persistent. Pistillate flowers c. 1.5 mm long; calyx urceolate, c. 1 mm long, with fine
silvery or ferrugineus hairs; ovary 2-carpellate; styles c. 1 mm long, free, persistent. Fruits
bilocular, 4-5 by 5-6 mm, green or yellowish-green at maturity, locules subglobose, without
processes, covered in yellowish-green, sticky exudate; pedicel slender, 5-8 mm long, with fine
silvery or ferrugineus hairs. Seeds c. 3 mm in diam., lenticular, black, shallowly pitted, encased
in a fleshy violet aril. [from http://www.nationaalherbarium.nl/Euphorbs/specM/MacarangaT.htm]
Ecology
Common early successional tree in lowland forests throughout west Malesia up to ca. 600 m
elevation. It occurs on a wide
range of substrates from nutrient-poor sandy soils to richer shale-derived soils, although it
seems to be more abundant on the former particularly in Borneo. It can also be found on soils
across a wide range of soil water levels. In some areas it occupies the margins of swampy ground,
although not usually in swamps, and in other areas it occurs on raised ridges of apparently low
soil water status. It is a very high-light demanding pioneer tree and grows quickly in good
conditions. It is one of a group of species that grows to be a relatively large tree. It can be
found in degraded land, logged forest and in large openings within primary forest where it may
persist for approximately 30 years.
Uses
Distribution
Peninsular Thailand and Malaysia, Sumatra and Borneo.
Local names
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