Ceratostylis Blume, Bijdr. (1825) 306. Lectotype: Ceratostylis graminea Blume
- Genus Apatales Blume ex Ridl., J. Linn. Soc.
- Genus Macrotis Breda, Gen. Sp. Orchid. Asclep. fasc. 4 (1830) s.n.
- Genus Ritaia King & Pantl., Ann. Roy. Bot. Gard. (Calcutta) 8 (1898) 156
- Genus Trigonanthus Korth. ex Hook.f., Fl. Brit. Ind. 5 (1890) 826 (nomen)
Sympodial epiphytes with tufted erect stems, or with pendulous rhizomes. Pseudobulbs consisting of one internode, very slender, terete or not, resembling a petiole, or pseudobulb much reduces; 1- or rarely 2-leaved at the apex. Leaves not sheathing at the base, deciduous, duplicate, dorsoventrally flattened or (almost) terete, leathery, glabrous. Inflorescences terminal, usually very short, carrying a single flower, often occurring in clusters. Flowers small to very small, resupinate or not. Sepals spreading or not, partly connate or free; lateral sepals connate; mentum often resembling a spur. Petals usually narrower than the sepals. Lip not mobile, entire or 3-lobed, without spur; apex usually swollen. Column at the apex with two erect arms; column-foot abbreviated; pollinia 8, solid; caudicles absent; stipe absent; viscidium present.