Dimorphocalyx Thwaites

Dimorphocalyx Thwaites View in CoL

Dimorphocalyx Thwaites (1861) View in CoL 278; Benth. (1880) 301; Hook.f.(1887) 403; Trimen (1898) 54, pl. 84; Brandis (1906) 581; Pax & K.Hoffm. (1911) 31; Ridl. (1924) 266; Gagnep. (1925) 295; Pax & K.Hoffm. (1931) 158; Airy Shaw (1967) 412; (1969) 123; (1972a) 251; (1972b) 92; Whitmore (1973) 86; Airy Shaw (1974) 328; (1975) 95; (1980a) 73; (1980b) 237; (1980c) 624; (1981) 286; (1982) 16; (1983) 20; Chakrab. & N.P.Balakr. (1990) 286;G.L. Webster (1994) 106; Philcox (1997) 107; Radcl.-Sm. (2001) 300; Phattar. & Chayam. (2005) 229. — Trigonostemon sect. Dimorphocalyx (Thwaites) Müll.Arg. (1865) 212; (1866) 1105. — Type: Dimorphocalyx glabellus Thwaites. View in CoL

Treelets to trees, dioecious (seldom monoecious). Indumentum of simple hairs, usually on young parts only. Stipules small, triangular, caducous. Leaves simple, alternate, petiolate, symmetric, margin entire to serrulate to serrate, with glands abaxially in the teeth or near the margin when entire; venation pinnate, slightly raised (to slightly sunken) above, raised below, secondary veins looped and joined near the margin, tertiary veins reticulate (or scalariform), veinlets reticulate. Inflorescences axillary or terminal, short, cymose, thyrsoid or narrowly paniculate when staminate, more or less racemose when pistillate, staminate flowers few together in cymose groups, pistillate flowers usually single per node or per inflorescence; bracts triangular to leaf-like. Flowers regular, 5-merous; calyx cup-shaped, (4–)5(–6)-lobed, lobes imbricate; petals 5, longer than calyx, imbricate, white. Staminate flowers: disc glands 5, free or zig-zagging around free stamens; stamens (7–)10–15(–c. 20), in 3 whorls, outer free, inner 2 with filaments connate into an androphore, anthers ellipsoid, dorsifixed, opening introrse via a lengthwise slit, thecae 2, parallel; pistillode absent. Pistillate flowers: petiole slightly broadening towards apex; disc annular; ovary ovoid, 3-locular, ovules 1 per locule, style generally absent, stigmas apically split. Fruits 3-lobed capsules, subglobose, dehiscing septicidally and (partly) loculicidally into separate or 2-valved cocci; pedicels elongating; sepals enlarging and enclosing fruit; wall thinly woody, exocarp often detaching; columella persistent, T-shaped. Seeds dry, obovoid, ecarunculate.

Distribution — A genus of c. 13 species, in SE Asia from Sri Lanka to Hainan to Australia. Eight species are recognised for Malesia.