Goniothalamus (Blume) Hook.f. & Thomson

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

Distribution

A large Old World tropical genus of c. 130 species with at least nine species in New Guinea. Goniothalamus grandiflorus Boerl. is cultivated in Lae Botanic Gardens.

Morphology General Habit

Trees or erect shrubs to 25 m

Morphology General Indumentum

Indumentum of simple hairs or simple mixed with stellate hairs

Morphology Leaves

Leaf blade large, secondary veins arcuately looped near margin

Morphology Reproductive morphology Inflorescences

Inflorescences axillary or extra-axillary, 1-flowered or several flowers in fascicles; pedicel bracteolate at base

Morphology Reproductive morphology Flowers

Flowers bisexual; sepals 3, valvate; petals 6, in 2 whorls, with each whorl valvate, outer petals flat, thick, inner petals smaller, base shortly clawed, connivent and mitreform (forming a cap); stamens many, anther locules linear or oblong, extrorse; connectives oblong or clavate, 3-angular, apex truncate or rarely rounded; carpels many, ovules 1–10 per carpel, ±basal, styles elongate, stigmas entire or apex 2-lobed

Morphology Reproductive morphology Fruits

Fruit apocarpous; monocarps subsessile to shortly stipitate, oblong-ellipsoid or ovoid

Morphology Reproductive morphology Seeds

Seeds 1–10 per monocarp.

Ecology

Goniothalamus are found in lowland and montant habitats including primary rain forest, swamp forest, montane forest, and savana woodland from sea level to c. 1700 m elevation.

Recognition

The genus can be recognised by the axillary, usually pendant flowers, either solitary or in fascicles (and often cauliflorous), the six petals in 2 whorls with the outer whorl larger the the inner whorl of petals which are clawed at the base and connivent (i.e., in contact with each other) forming a mitre-like dome over the stamens and carpels.