20. Spiranthes Richard, De Orchid. Eur. 20, 28, 36. 1817.
绶草属 shou cao shu
Authors: Xinqi Chen, Stephan W. Gale & Phillip J. Cribb
Aristotelea Loureiro (1790), not Aristotela Adanson (1763), nor Aristotelia L’Héritier (1785-1786, nom. cons.); Gyrostachys Persoon ex Blume; Ibidium Salisbury ex Small; Monustes Rafinesque; Orchiastrum Séguier.
Herbs, terrestrial, acaulescent. Roots fasciculate, fusiform, fleshy, glabrous. Leaves basal, forming a rosette, linear, elliptic, or broadly ovate, rarely subcylindric, base sheathing. Inflorescence terminal, racemose with many small flowers arranged spirally around rachis. Flowers resupinate, horizontal or nodding, not opening widely, small; ovary twisted, fusiform. Sepals free, narrowly elliptic to lanceolate, subsimilar; dorsal sepal erect, often connivent with petals and forming a hood; lateral sepals dilated or sometimes saccate at base. Petals erect, oblanceolate, recurved; lip entire or obscurely 3-lobed, shortly clawed, apex recurved, undulate, lateral margins embracing column; disk usually papillose, with 2 fleshy glands at base. Column clavate, ventrally pubescent; anther erect, 2-locular, on dorsal surface of column; pollinia 2, each 2-partite, granular-farinaceous, with or without short caudicle and attached to narrow viscidium; rostellum erect, 2-lobed at apex after removal of viscidium; stigma suborbicular to elliptic. Capsule ellipsoid.
About 50 species: mainly in North America, with a few species in Africa, Asia, Australia, Central and South America, and Europe; three species (two endemic) in China.
