Chlorosa Blume; Zosterostylis Blume.

Herbs, terrestrial. Rhizome horizontal or ascending, short, densely noded, producing aerial shoots from apical nodes; roots fasciculate, long, fleshy. Leaves basal, elliptic to ovate-lanceolate, base long attenuate into erect petiole-like stalks, with or without loosely sheathing cataphylls at base. Inflorescence erect or ascending, terminal, racemose, several flowered, with sheathing cataphylls at base and scattered sterile bracts along peduncle; floral bracts sheathing. Flowers not resupinate; pedicel and ovary erect, arcuate. Sepals and petals subsimilar, free, spreading, very narrow, margin often involute. Petals often slightly shorter and smaller than sepals; lip attached to base of column, entire, tapering toward apex, basally expanded and embracing column, spurless; disk usually with longitudinal ridges or elongate calli. Column short, with lateral wings; anther terminal, erect, 4-locular; pollinia 4, in 2 pairs, clavate, granular-farinaceous, attached to solitary viscidium; stigma entire, convex, fleshy; rostellum erect, broad and stout.

About 20 species: mainly in tropical Asia, from India and Sri Lanka to the Philippines, Australia, and the Pacific islands; two species in China.

(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Stephan W. Gale, Phillip J. Cribb)