18. Anoectochilus Blume, Bijdr. 411. 1825.
金线兰属 jin xian lan shu
Authors: Xinqi Chen, Stephan W. Gale, Phillip J. Cribb & Paul Ormerod
Herbs, terrestrial. Rhizome creeping, terete, several noded, fleshy; roots narrowly filiform to fibrous, villous, arising singly from rhizome nodes. Stem erect or ascending, with 1 to a few loose tubular sheaths at base, and a few clustered subrosulate leaves, glabrous. Leaves green to purplish black with white, pinkish, or golden reticulate venation on adaxial surface, ovate or elliptic, velvety and often slightly fleshy, with a long petiole-like base dilating into tubular amplexicaul sheath. Inflorescence erect, terminal, racemose, pubescent; peduncle with a few scattered sheathing bracts; rachis laxly 2-10-flowered. Flowers resupinate or not; ovary slender, twisted or not. Sepals free, similar, often widely spreading, outer surface usually pubescent; dorsal sepal forming a hood with petals. Petals obliquely ligulate-oblong, membranous; lip basally adnate to base of column, distinctly 3-partite, with an exserted conic to cylindric spur at base; hypochile subtubular, lateral margin erect; mesochile short to elongate, canaliculate, both external lateral margins with an entire, pectinate or filamentous flange; epichile entire to deeply 2-lobed, lobes divergent, rarely divided; spur containing a pair of irregular calli or septa. Column short, dorsally dilated, ventrally with 2 intramarginal, lamellate or fleshy appendages (wings); anther erect, ovoid, 2-locular; pollinia 2, clavate, sectile, granular-farinaceous, each attenuate into a narrow stalk attached to a solitary ovate viscidium; rostellum usually erect, remnant shortly bifid; stigma lobes 2, separate, convex, placed laterally toward apex of column. Capsule narrowly ellipsoid.
About 30 species: India and the E Himalayas, through S and SE Asia to Australia and the SW Pacific islands; 11 species (seven endemic) in China.
The taxonomic distinction between Anoectochilus and its close ally Odontochilus has been problematic, and members of the latter (and other closely related genera) have frequently been lumped with those of the former. Anoectochilus is circumscribed here in line with Pridgeon et al. (Gen. Orchid. 3: 69-72. 2003), which regards the ornate venation of the leaves, the conic spur that is exserted beyond the bases of the lateral sepals, and the widely separated stigma lobes that are placed laterally toward the apex of the column as definitive generic characters. Members of Odontochilus, in contrast, lack colored reticulate venation on their leaves, possess only a short saccate hypochile that is enclosed within the bases of the lateral sepals, and have confluent or narrowly separated stigma lobes that are positioned directly beneath the rostellum. Further work is clearly required to better resolve generic and specific affinities; the endemic species of China, in particular, remain poorly known.
A photograph labeled "Anoectochilus roxburghii" by X. H. Jin, X. D. Zhao, and X. C. Shi (Native Orchids Gaoligongshan Mts. China, 79. 2009) appears to represent A. calcareus Averyanov (Bot. Zhurn. (Moscow & Leningrad) 81(10): 75. 1996). This would be a new record for China, but it was discovered too late to be given a full entry in the present treatment.