12. Breynia J. R. Forster & G. Forster, Char. Gen. Pl. 73. 1775.
黑面神属 hei mian shen shu
Authors: Bingtao Li & Hans-Joachim (Hajo) Esser
Melanthesa Blume; Melanthesopsis Müller Argoviensis.
Shrubs or trees, monoecious; indumentum of simple hairs or absent. Leaves simple, alternate, distichous, petiolate; stipules triangular, ± caducous; leaf blade entire, abaxially drying dirty brownish and often glaucous-papillate, adaxially often drying blackish, pinnately veined. Inflorescences axillary, male flowers in few-flowered clusters in proximal axils, sometimes in small bracteate racemes, female flowers solitary in distal axils. Male flowers: calyx turbinate, funnelform, or hemispheric, fleshy, apex usually shortly 6-lobed, lobes usually incurved and concealing stamens; petals absent; disk lobes scalelike, at base of calyx lobes; stamens 3; filaments connate into cylindric column with parallel sessile anthers along sides; anthers 2-locular, longitudinally dehiscent; pistillode absent. Female flowers: calyx turbinate, hemispheric, campanulate, radial, or cup-shaped, 6-dentate to (5 or)6-fid, persistent, accrescent into saucer-shape or disk; ovary globose, truncate, or depressed, 3-locular; styles 3, bifid at apex, inserted within apical depression with lobed margin; ovules 2 per locule. Fruit usually a berry, globose or depressed globose, red, indehiscent, exocarp ± fleshy, harder when dry, with 3-6 trigonous cocci when mature. Seeds sharply 3-angled, yellow or reddish, smooth; testa thinner; caruncle absent; endosperm copious, fleshy; embryo curved; cotyledon slightly broad and flattened. n = 13, 16.
Between 26 and 30 species: tropical Asia, Australia, Pacific islands; five species in China.
Breynia disticha J. R. Forster & G. Forster f. nivosa (W. Bull) Croizat ex Radcliffe-Smith, the "snow bush," is a widely grown ornamental shrub, often as a low hedge plant, with membranous, green-white-red variegated leaves and otherwise similar to B. retusa but never setting fruits in China.
Initial observations (Kawakita & Kato, Amer. J. Bot. 91: 1319-1325. 2004) suggested that there is a symbiotic relationship between species of Breynia and moths of the genus Epicephala similar to that observed in Glochidion.
