15. Chamaegastrodia Makino & F. Maekawa, Bot. Mag. (Tokyo). 49: 596. 1935.
叠鞘兰属 die qiao lan shu
Authors: Xinqi Chen, Stephan W. Gale & Phillip J. Cribb
Herbs, small, holomycotrophic. Rhizome coralloid, fleshy, sometimes branching. Stem ascending or erect, yellow to pale brownish red, tinged purplish red, glabrous, leafless, with overlapping sheathing scales. Inflorescence erect, terminal, racemose, glabrous, several to many flowered; floral bracts membranous, glabrous. Flowers erect, not resupinate, small; ovary fusiform, not twisted, glabrous. Sepals free, ± similar, glabrous; dorsal sepal ovate, usually connivent with petals; lateral sepals enclosing base of lip. Petals oblong to ligulate-lanceolate, nearly as long as dorsal sepal, much narrower than sepals, membranous; lip usually 3-partite and T-shaped, or rarely entire, ovate with unlobed apex; hypochile concave-saccate, containing 2 fleshy calli toward base (1 on either side of midvein); mesochile subtubular, sometimes with narrow lamellate flanges along external lateral margins; epichile bilobed. Column stout, ventrally with 2 triangular-falcate appendages (wings) toward apex; anther ovoid, 2-locular, sessile or rarely attached to column via a slender filament; pollinia 2, each longitudinally parted, granular-farinaceous, sectile, attenuate into slender stalk and attached to a solitary viscidium; rostellum long or short, remnant entire to shortly bifid; stigma lobes confluent to narrowly separated, small to relatively large, raised, placed toward apex of column beneath lower margin of rostellum.
About three species: China, India, Japan, Myanmar, Thailand, Vietnam; three species (one endemic) in China.
Despite the leafless, mycotrophic habit, the shape of the lip and the structure of the column indicate that Chamaegastrodia is closely related to Odontochilus. Indeed, taxa previously included here (see Seidenfaden, Nordic J. Bot. 14: 293-301. 1994) that were first described in the now defunct genus Evrardia have been transferred recently to Odontochilus (see Pridgeon et al., Gen. Orchid. 3: 74. 2003). The shape and placement of the column wings in the remaining three species of Chamaegastrodia are thought to distinguish them from the rest of Odontochilus, though more detailed study, including molecular data, may reveal this distinction to be artificial.