Description from Flora of China
Adactylus (Endlicher) Rolfe; Apostasia [unranked] Adactylus Endlicher; Niemeyera F. Mueller (1867), not F. Mueller (1870).
Herbs, erect, glabrous. Rhizome scaly, producing a few proplike roots; roots sometimes bearing tubers. Stem simple or branched, rather slender, leafy. Leaves clustered or well spaced, plicate, usually recurved along margins, forming a tubular awn at apex, base contracted and then dilating and amplexicaul. Inflorescences terminal or subterminal, often arching or sometimes pendulous, usually branched; floral bracts relatively small. Flowers erect, not resupinate, almost actinomorphic; ovary 3-locular, slender, not distinct from pedicel. Sepals similar, cymbiform, slightly fleshy. Petals similar, yellow to white, cymbiform; lip similar to petals though sometimes slightly larger. Column erect or curved, with 2 fertile stamens, with or without a central staminode; anthers clasping style, with 2 locules of subequal to distinctly unequal length; filaments usually short, adnate to style; staminode (if present) opposite to dorsal sepal; pollen not cohering to form pollinia; style cylindric; stigma terminal, capitate. Fruit a capsule, narrowly cylindric, shallowly longitudinally 3-ribbed. Seeds black at maturity, with a rigid testa.
About seven species: NE India, Nepal, and Bhutan, north to S Japan, through SE Asia to New Guinea and N Australia; three species (one endemic) in China.
(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Stephan W. Gale, Phillip J. Cribb)