Amaracarpus Blume

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

A genus of c. 31 species: Seychelles, Andaman & Nicobar Islands through Myanmar to Malesia, Northern Australia and the Pacific Islands; c. 21 arborescent species occur in New Guinea (18 of these are endemic).

Morphology General Habit

Monopodial trees or shrubs to 8 m; branches opposite or alternate and plagiotropic, distinctive side shoots or brachyblasts often present (leaves smaller than main branch)

Morphology General

Raphides present. Stipules sheathing for c. ½ or > ½ of their length or splitting when mature, entire or bifid, sometimes with 1–2 bristles at tip

Morphology Leaves

Leaves distichous, venation brochidodromous, intramarginal vein present or absent, domatia absent. Inflorescences terminal or axillary, inflorescence simple or 3-several flowered

Morphology Reproductive morphology Flowers

Flowers small, 4-merous, valvate in bud; calyx lobes longer than the tube; corolla light green to white, glabrous or with a ring of hairs in throat, lobes ±equal to or shorter than tube, reflexed when mature; ovary 2-locular, disk present; stigma 2-lobed

Morphology Reproductive morphology Fruits

Fruit a fleshy drupe, yellow-green ripening to orange-red, 2 pyrenes, each with 3–4 longitudinal ridges or ±smooth

Morphology Reproductive morphology Seeds

Seed coat smooth.

Ecology

Found in the understorey layer of both disturbed and primary, humid, evergreen forests.

Recognition

The genus is characterised by the 4-merous, valvate flowers, orange-red fruits with 2 ridged or smooth pyrenes, and especially the vegetative architecture with the branches held horizontally with brachyblasts (distinctive shortened side shoots bearing comparatively smaller leaves in clusters). There is sometimes a foetid aroma when plant is damaged. Similar to Dolianthus, see that genus for differences.