Mesoclastes Lindley.

Herbs, epiphytic or lithophytic, monopodial. Stems erect or climbing, often branched at base and tufted, some with a single shoot, terete, slender, usually stiff, enclosed in leaf bases. Leaves many, well spaced, linear, terete, distichous, facing all directions or secund, fleshy, jointed and sheathing at base. Inflorescence axillary, racemose, dense, subsessile, fewer than 10-flowered; peduncle and rachis attenuate. Flowers usually small, fleshy. Sepals and petals free, similar or petals longer and narrower, spreading; lateral sepals often dorsally carinate or narrowly winged toward apex. Lip pendulous, fleshy, fixed immovably to base of column, often distinctly divided by a groove into basal hypochile and apical epichile; hypochile often concave, base sometimes with lateral lobes embracing column; epichile often extending forward, adaxially often longitudinally wrinkled or grooved. Column subcylindric, short, stout, foot absent; rostellum short, wide, apex subtruncate; pollinia 2, waxy, globose, porate, attached by a short and broad stipe to a solitary, short, broad viscidium.

Luisia macrotis H. G. Reichenbach (Gard. Chron. 1869: 1110. 1869) was recently recorded from W Yunnan (Lushui: Gaoligong Shan, 2500 m) by X. H. Jin, H. Li, and D. Z. Li (Acta Phytotax. Sin. 45: 805. 2007). The species otherwise occurs in India (Assam), Laos, Thailand, and Vietnam.

Reviewer L. Averyanov notes that Luisia appressifolia Averyanov (Lindleyana 15(2): 79. 2000), described from N Vietnam, should also occur in S China. However, the present authors could not substantiate this assertion because they found no relevant specimens.

About 40 species: Bhutan, China, India, Indochina, Indonesia, Japan, Malaysia, New Guinea, Pacific islands, Philippines, Sri Lanka, and Thailand; 11 species (five endemic) in China.

(Authors: Chen Xinqi (陈心启 Chen Sing-chi); Jeffrey J. Wood)