Terrestrial herbs with short rhizomes and slender elongated roots. Stems erect, slender, with single leaf in middle part. Leaves narrow, flat, base sheathed and enclosing stem, not articulated. Flowers usually solitary, terminal, medium to large, with an abscission layer between ovary and perianth; bracts leaf-like; sepals and petals subequal, free, usually narrow; lip erect at base of column, without spur, 3lobed or undivided, disc often with raised keels or fleshy hairs; column elongate, wingless, slightly dilated above, without foot; anther terminal, incumbent; pollinia 2, soft and mealy, without caudicle and viscidium; stigma entire; rostellum short and broad.
About 4 species, temperate eastern Asia and North America. One species in Taiwan.