Centrosis sylvatica Thouars
Plant 40-70 cm tall. Rhizomes not distinct. Roots slender, ca. 2 mm in diam. Pseudobulbs closely aggregated, clavate or elongate conic, 2-4 cm long, with 3 or 4 nodes, covered by leaf bases. Leaves 46, fascicled, elliptic or oblanceolate, 20-40 cm long, 5-12 cm wide, apex acute or acuminate, base decurrent into short petioles, slightly repand or undulate, mainly 5-nerved, distinctly plicate; petiole 8-12 cm long. Scapes arising from leaf axil, 30-50 cm tall, 4 mm in diam., short pubescent, with 3-6 scales below, flowering bearing portion ca. 10 cm long; bracts lanceolate, 1-2 cm long, upper ones smaller; pedicel and ovary 2.5-2.8 cm long, sparsely short pubescent. Flowers +/- dense, violet or purple, later turning to pale orange, ca. 3.5 cm in diam.; sepals nearly equal, elliptic, 1.5-2 cm long, 8-10 mm wide, acute or apiculate, 3-nerved; petals obovate, 16-18 mm long, 7 mm wide, acute or obtuse at apex, narrowed at base, 1-nerved; lip with long spur, obovate or obtriangular in outline, 1.2-2 cm long, 1-1.5 cm wide, 3-lobed, lateral lobes smaller, oblong, linear or falcate, central lobe clawed rhombic to stalked reniform, larger than lateral ones, emarginate or retuse at apex, contracted at base, sometimes with distinct falcate, truncate lobelets, disc with numerous small callose warts aggregated near base, spur 2.4-4 cm long, often curved, rarely coiled; column ca. 3-4 mm long, fused with base of lip; anther cordate, 2celled; pollinia clavate, 2 mm long, with small rounded viscidium; stigma divided into 2 parts near entrance of spur; rostellum white, deeply 2-lobed, lobes rounded-truncate at apex.
TAIPEI: Tatungshan, Su 546; Poloshan, Su & Chen 7335. ILAN: Shihtu, Su 640; Nanao, Su et al. 8005. NANTOU: Hoshe, Kawakami & Mori s. n. Mar 1908. PINGTUNG: Laufushan, Su & Chen 7970. TAITUNG: Chingshuiying, Su 114; Chenkuanaoshan, Yamamoto s. n. Aug 1931; Lanyu Is., Lin s. n. Aug 1972.
Tropical Africa and Madagascar, eastward through India, Sri Lanka, the Himalaya, to southern China, southern Japan, the Ryukyus, Thailand and Malaysia. Taiwan, in forests, 1,000-2,000 m, throughout the island.