Brachychiton Schott & Endl.

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

Distribution

A genus of 31 species, primarily Australian but the range extending to New Guinea. Two species (one endemic) occur in New Guinea: Brachychiton carruthersii F.Muell. and B. velutinosus Kosterm.

Morphology General Habit

Trees to 25 m in New Guinea occasionally shrubs, deciduous or evergreen, trunk cylindrical or swollen (rare in New Guinea)

Morphology General Indumentum

Indumentum of stellate hairs

Morphology Leaves Stipules

Stipules present, caducous or persistent

Morphology Leaves

Leaves alternate, simple, 3-lobed (in New Guinea), margin entire. Inflorescence axillary or ramiflorous, paniculate, cymose botryoidal or triads. Flowers unisexual, with articulated pedicels; calyx (4–)5(–8)-lobed, campanulate, red to greenish white; nectaries present or absent; androgynophore present, stamens 10–30, in 1 or several whorls, staminodes sometimes present; ovary of 5 carpels, ovules 2–many per carpel, styles free or connate

Morphology Reproductive morphology Fruits

Fruit of up to 5 woody, dehiscent follicles, hairy on the inner surface

Morphology Reproductive morphology Seeds

Seeds few to many per follicle, enclosed in persistent exotesta.

Ecology

In New Guinea, Brachychiton has been collected from a range of lowland habitats including monsoon and rain forests, and those that are seasonally inundated; from sea level to 600 m.

Recognition

The genus is distinguished from Sterculia by follicle and seed characters. Brachychiton has follicles which are dark brown or black when mature and hairy inside (red and glabrous inside in Sterculia) and the seeds abscise before the fruit dehisces (in Sterculia the seeds remain attached to the pericarp by their funicles after dehiscence) and in Brachychiton the seeds are enclosed in a chartaceous exotesta (absent in Sterculia).