Thrixspermum Lour., Fl. Cochinch. 2 (1790) 519
- Genus Cylindrochilus Thw., Enum. Pl. Zeyl. (1861) 307
- Genus Dendrocolla Blume, Bijdr. (1825) 286
- Genus Orsidice Rchb.f., Bonplandia 2 (1854) 93
- Genus Ridleya (Hook.f.) Pfitzer in Engl. & Prantl, Naturl. Pflanzenfam.
- Genus Thylacis Gagnep., Bull. Mus. Hist. Nat. (Paris)
Monopodial epiphytic or sometimes terrestrial plants. Stem short to much elongated. Leaves few to many, arranged in two rows, sheathing at the base, glabrous, deciduous, duplicate, leathery. Inflorescence lateral, a dense, few- to many-flowered raceme, with the flowers opening in succession. Bracts often laterally flattened and then arranged in two rows. Flowers small to rather large, ephemeral, resupinate, usually whitish or yellowish, often with brown spots. Sepals free. Petals free, usually fairly similar to the dorsal sepal but often slightly narrower. Lip without spur, not mobile, concave, in the centre usually with a callus. Column-foot present. Pollinia 4, unequal, arranged in two bodies, solid, caudicles absent, stipe present, viscidium present.
Species present in New Guinea: