1. Arachnis labrosa (Lindley & Paxton) H. G. Reichenbach, Bot. Centralbl. 28: 343. 1886.
窄唇蜘蛛兰 zhai chun zhi zhu lan
Stems to 50 cm, 7-10 mm in diam., rigid, with many nodes and leaves. Leaves distichous; leaf blade lorate or linear, 15-30 × 1.6-2.2 cm, leathery, obtusely unequally bilobed. Inflorescence arising from within leaf sheath, ascending, racemose, to 1 m, occasionally branched, laxly many flowered; floral bracts reddish brown, broadly ovate, 5-8 mm, obtuse. Flowers pale yellow with reddish brown spots or markings mostly along margins and at apex, or greenish yellow without red-brown markings; pedicel and ovary brown, ca. 2 cm, slender. Sepals oblanceolate, ca. 18 × 3 mm, obtuse. Petals oblong, 9-11 × 2-5 mm, subacute; lip ca. 1 cm, fleshy, 3-lobed; lateral lobes erect, subtriangular, small, ca. 2 mm wide at base, obtuse; mid-lobe ligulate, fleshy, acute or obtuse, with a thickened appendage abaxially near apex, base with 2 retrorse calli on both sides, spurred; spur saccate-conic, 4-5 mm, thickly fleshy, its entrance ± covered by calli. Column ca. 6 × 4 mm, stout, base with an inconspicuous foot; rostellum triangular, apex widely emarginate; stipe subovate-triangular, ca. 1 mm; viscidium nearly suborbicular. Fl. Aug-Sep. 2n = 38.
Epiphytic on tree trunks at forest margins, lithophytic on rocks in valleys; 600-1200 m. Guangxi, Hainan, C and S Taiwan, S Yunnan [Bhutan, NE India, ?Japan (Ryukyu Islands), Myanmar, S Vietnam].