Description from Flora of China
Trees or shrubs, rarely herbs or liana; young growth usually stellately hairy; bark mucilaginous and rich in fibers. Leaves alternate; stipules usually present caducous; leaf blade simple, rarely palmately compound, entire, serrate, or parted. Inflorescence axillary or rarely terminal, paniculate, corymbose, racemose, or cymose, rarely solitary. Flowers unisexual, bisexual or polygamous. Sepals (3-)5, ± connate, rarely free, valvate. Petals 5 or lacking, free or adnate to base of androecium, convolutely imbricate. Androgynophore usually present; filaments usually connate into a single tube; staminodes 5, tonguelike or filiform, opposite to sepals, sometimes lacking; anthers 2-celled, longitudinally dehiscent. Pistil consisting of 2-5(or 10-12) ± connate carpels, or a single carpel; ovary superior, 2-5(or 10-12)-loculed; ovules 2 or more per locule; style 1 or as many as carpels. Fruit usually a capsule or follicle, dehiscent or indehiscent, very rarely a berry or nut. Seeds with abundant endosperm or endosperm lacking; embryo straight or curved.
The Chinese genera fit into four distinct clades which can be treated as subfamilies of an enlarged Malvaceae or as distinct families. These are Sterculioideae/Sterculiaceae s.s. (genera 1-4), Helicteroideae/Helicteraceae (genera 5 and 6), Byttnerioideae/Byttneriaceae (genera 7-13), and Dombeyoideae/Pentapetaceae (genera 14-19).
The record of Hildegardia Schott & Endlicher in China (Bayer & Kubitzki, Fam. Gen. Vasc. Pl. 5: 265. 2003) was based on H. major (W. W. Smith) Kostermans, which is here included within Firmiana.
Hsue Hsiang-hao. 1984. Sterculiaceae. In: Feng Kuo-mei, ed., Fl. Reipubl. Popularis Sin. 49(2): 112-189.
About 68 genera and ca. 1100 species: tropics and subtropics of both hemispheres, a few in temperate regions; 19 genera (two introduced) and 90 species (39 endemic, three introduced) in China.
(Authors: Tang Ya (唐亚); Michael G. Gilbert, Laurence J. Dorr)