Trees [shrubs]. Leaf blades unlobed or lobed, ultimate margins entire or serrate. Inflorescences axillary or terminal, paniculate [racemose]. Flowers usually functionally unisexual, rarely bisexual; epicalyx absent; sepals persistent or late-deciduous, (4–)5(–8), connate, petaloid, nectaries usually at base on adaxial surface, sometimes absent; petals absent; androgynophore present; stamens [4–]10–30, basally connate; anthers 2-thecate; staminodes absent; gynoecium apocarpous. Fruits follicles [nuts]. Seeds 1–22[–144], glabrous or hairy.

Distribution

Asia, Pacific Islands, Australia, pantropical.

Discussion

Genera ca. 12, species ca. 400 (2 genera, 2 species in the flora).

Genera in Sterculioideae historically have been recognized as a morphological group (H. W. Schott and S. L. Endlicher 1832; A. L. Takhtajan 1997; P. Wilkie et al. 2006) due to the presence of mostly unisexual flowers with androgynophores and without petals. Individually, these elements are found throughout Malvaceae; their combination is exclusive to Sterculioideae. Generic relationships within Sterculioideae are complicated. Firmiana is closely related to Hildegardia Schott & Endlicher and, as currently circumscribed, is not monophyletic (Wilkie et al.).

Selected References

Wilkie, P. et al. 2006. Phylogenetic relationships within the subfamily Sterculioideae (Malvaceae/Sterculiaceae-Sterculieae) using the chloroplast gene ndhF. Syst. Bot. 31: 160–170.

Lower Taxa

Brachychiton, Firmiana

Key

1	Follicles woody; seeds hairy.	Brachychiton
1	Follicles chartaceous; seeds glabrous.	Firmiana