Esterculiaceae

STERCULIACEAE
梧桐科 wu tong ke Tang Ya (唐亚)1; Michael G. Gilbert2, Laurence J. Dorr3 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, longitudinallydehiscent. 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.
About 68 genera and ca. 1100 species: tropics andsubtropics of both hemispheres, a few in temperate regions; 19 genera (two introduced) and 90 species (39 endemic, three introduced) in China. 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.

1a. Flowers withoutpetals, unisexual or polygamous; fruit apocarpous with separate follicles (Sterculioideae). 2a. Follicles not dehiscent, with wing or prominent keel, 1-seeded; leaf blade abaxially with dense silver-white or yellow-brown scales ................................................................................................................................................... 4. Heritiera 2b. Folliclesdehiscent, without wing or keel, 1- or more seeded; leaf blade abaxially without scales. 3a. Seeds long-winged; fruit woody ......................................................................................................................... 1. Pterygota 3b. Seeds not winged; fruit leathery or membranous, rarely woody. 4a. Fruit leathery, rarely woody, dehiscent when mature.................................................................................... 2. Sterculia 4b. Fruit membranous, dehiscent before maturity and foliaceous ...................................................................... 3. Firmiana 1b. Flowers with petals, bisexual; fruit usually syncarpous, sometimes dividing into separate mericarps. 5a. Ovary on long androgynophore, at least 2 × as long as ovary, oftenlonger than calyx and petals. 6a. Capsule membranous, inflated; seeds 1(or 2) in each cell (Byttnerioideae) ..................................................... 7. Kleinhovia 6b. Capsule more or less woody, never membranous, not inflated; seeds 2 or more in each cell (Helicteroideae). 7a. Trees or large shrubs, 6–25 m tall; seeds 1 or 2 per locule, with obvious membranous wing, more than 20 mm;inflorescences terminal; anthers sessile on filament tube or nearly so ............................................ 5. Reevesia 7b. Shrubs or subshrubs, 0.45–2 m tall; seeds many per locule, without wing, less than 4 mm; inflorescences axillary; anthers with distinct free filaments ................................................................................................ 6. Helicteres 5b....