Gonocaryum Miq.

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

Distribution

An Asian genus of about 12 species from Myanmar and southern China and Taiwan through to the Bismarck Archipelago; Gonocaryum litorale (Blume) Sleumer is the only species in New Guinea (an additional species was described from a single type specimen, now lost.)

Morphology General Habit

Shrubs or trees to 20(–30) m

Morphology Leaves

Leaves spirally arranged, entire, penninerved; petiole yellow and always characteristically transversely wrinkled

Morphology Reproductive morphology Inflorescences

Inflorescences axillary or from defoliate axils below the leaves, spikes to 30 cm long

Morphology Reproductive morphology Flowers

Flowers unisexual (plants dioecious), sessile; calyx small, 5-lobed, persistent; petals 5, valvate, united up to the lower half, sometimes papillose inside; staminate flowers with 5 stamens, filaments adnate to the petals; anthers oblong-elliptic, introrse, rudimentary ovary hairy; pistillate flowers with 5 rudimentary stamens, ovary sessile, style short-conical, stigma relatively large and pad-like

Morphology Reproductive morphology Fruits

Drupe ellipsoid to obovoid or oblongoid, shiny and orange to reddish when mature, endocarp angular with few to numerous ribs; exocarp spongy

Morphology Reproductive morphology Seeds

Seed 1, ellipsoid.

Ecology

This genus is known from a common and wide-ranging species (Gonocaryum litorale (Blume) Sleumer) found in the understorey of a variety habitats including coastal and swamp forests, to c. 1700 m.

Recognition

It can be recognised by the simple, alternate exstipulate leaves which are usually coriaceous and glossy green above contrasting with the yellow, transversely wrinkled petiole, the flowers are borne on pendulous inflorescences and are usually pale green or white. The drupaceous fruits are orange to red when mature with spongy flesh (the drupes are able to float).