Calanthe pachystalix Rchb. f. ex Hook. f.
Plants 30-50 cm tall. Rhizomes not distinct. Pseudobulbs clavate, 2-4 cm long, ca. 1 cm thick, with 2-4 nodes. Leaves 6-10, nearly distichous, overlapping pseudobulbs at their bases, linear, 20-60 cm long, 1-4 cm wide, membranaceous, mainly 3-nerved, without distinct petiole. Scapes erect, slender, 4080 cm tall, terete; peduncle short pubescent; rachis ca. 30 cm long; bracts linear-lanceolae, 7-15 mm long, 3-4 mm wide; ovary and pedicel 8-15 mm long, shortly pubescent. Flowers numerous, crowded, pale green or whitish, not resupinate, with reflexed sepals and petals; sepals obovate or oblong, 7-9 mm long, 3-5 mm wide, acute or obtuse at apex; lateral sepals similar but often slightly wider; petals linear-spatulate, 7-9 mm long, 2-3 mm wide, acute at apex, cuneate at base; lip white, spurred, broadly obtriangular, 5-9 mm long, 11-15 mm wide, 3-lobed, lateral lobes falcate-oblong, obtuse at apex, entire or irregularly undulate, central lobe obtriangular, deeply 2-lobed, disc with a large white 3-lobed callus and many small yellowish calli near base; spur 7-14 mm long, glabrous or sparsely pubescent; column ca. 35 mm long, connate with base of lip; anther cordate; pollinia unequal, in 2 groups, 2 long and 2 short, connected through short caudicles to oblong viscidium; stigma 2-parted; rostellum, bifid.
TAIPEI: North Chiatienshan, Su & Chen 7173*; Tatungshan, Su 9029. TAOYUEN: Lalashan, Matuda s. n. Jul 1919. ILAN: Nanhutashan, Su 8323; Su & Chen 9081. NANTOU: Chitou, Su 679; Shenmu to Tataka, Su & Chen 9088. HUALIEN: Chungyungchienshan, Su 735; Lakulakuchi, Su & Hsu 8275. PINGTUNG: North Tawushan, Su & Chen 9363.
India, the Himalaya, southern China, and Japan. Taiwan, in forests at 1,200-2,000 m throughout the island.
The shape and the size of the lobes of the lip in this species is highly variable. The lobules of the central lobe are sometimes greatly reduced. Such variation can be found within a population.