Description from Flora of China
Blephariglottis Rafinesque; Gymnadeniopsis Rydberg; Limnorchis Rydberg; Lysiella Rydberg; Perularia Lindley; Piperia Rydberg; Tulotis Rafinesque.
Herbs, terrestrial, small to medium-sized. Rootstock composed of a slender, creeping stolon, or of a fusiform or ovoid tuber, fleshy, sometimes fascicled, usually with several filiform roots at neck. Stem erect or ascending, with 1 to several leaves. Leaves basal or cauline, alternate or rarely subopposite, elliptic, ovate-elliptic, or linear-lanceolate, sheathing at base. Inflorescence terminal, glabrous; peduncle cylindric, with 1 or more often foliaceous bracts; rachis few to many flowered, lax or dense; floral bracts usually lanceolate, herbaceous. Flowers often sweetly scented, resupinate, white, green, yellow-green, rose-pink, or orange, variable in size; pedicel and ovary twisted, arcuate toward apex, cylindric to fusiform, glabrous. Dorsal sepal usually connivent with petals and forming a hood, concave, short, margin ciliate or glabrous; lateral sepals spreading or reflexed, longer than dorsal sepal, margin ciliate or glabrous. Petals usually narrower than sepals; lip spreading or pendulous, sometimes strongly deflexed, entire and ligulate, sometimes with small lateral lobes at base, or divided and fimbriate to varying degrees, usually slightly fleshy, sometimes with a central thickening, sometimes with a callus on disk, spurred at base; spur usually very long and filiform or narrowly cylindric, rarely short and conic. Column short, stout, with a pair of staminodes at base of anther; anther erect, broad, with 2 parallel or divergent locules, connective conspicuous; pollinia 2, sectile, clavate, granular-farinaceous, each with conspicuous caudicle and naked viscidium; rostellum triangular, with 2 divergent arms at base; stigma lobes confluent, concave, lying below rostellum and fused with its lower part, or on a convex surface surrounded by rostellum, or sometimes of 2 separate, raised lobes placed in front of mouth of spur. Capsule erect.
Placement of some of the small-flowered and shortly spurred species here as opposed to in Peristylus is questionable, though critical re-evaluation currently is hampered by the very limited material (particularly of the endemic Chinese species) available for study.
About 200 species: throughout Europe and N Africa, north temperate Asia, the Malay Archipelago, and New Guinea, and Central and North America; 42 species (19 endemic) in China.
(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Stephan W. Gale, Phillip J. Cribb)