Sp. Pl. 4 (1805) 44
Sympodial terrestrial plants, often with a subterranean tuber. Stem very short to elongated, one- to several-leaved. Leaves sheathing at the base, often spirally arranged, glabrous, persistent, convolute, herbaceous. Inflorescence a terminal, few- to many-flowered raceme. Flowers small to medium-sized, resupinate, usually green or white, sometimes with orange or pink lip. Sepals free. Petals free, often with two or more narrow lobes. Lip spurred, not mobile. Column-foot absent. Pollinia 2, sectile, caudicles present, stipe absent, viscidium present. Caudicles inserted in a grooved projection called the anther channel. Stigma with two widely separated lobes, each on top of a distinct stalk, the so-called stigmatophore, which is free from the lip.
Tropics and subtropics, world wide. About 600 species; in New Guinea c. 20 species.
Terrestrial in lowland and montane forest and in open places along streams, on hillsides, in seasonally dry grassland, etc.
The largest genus of terrestrial orchids in the world, often with intricately lobed and fringed flowers, which are mostly green or white. Peristylus is very closely related but differs in that the stigmatophores are not free, as in Habenaria, but adnate to the base of the lip.