Description from Flora of China
Callista adunca (Wallich ex Lindley) Kuntze; Dendrobium aduncum var. faulhaberianum (Schlechter) Tang & F. T. Wang; D. faulhaberianum Schlechter.
Stems pendulous, sometimes upper part ± curved, pale yellow when dry, cylindric, 50-100 cm, 2-5 mm in diam., unbranched, with many nodes, internodes 3-3.5 cm. Leaves oblong or narrowly elliptic, 7-10.5 × 1-3.5 cm, with clasping sheaths at base, apex acute. Inflorescences often several, arising from upper part of deciduous or leafy old stem; rachis ± porrect, 1.5-4 cm, slender, sparsely 1-6-flowered; peduncle 5-10 mm, base with 3 or 4 membranous sheaths 2-3 mm; floral bracts ovate-lanceolate, 5-7 mm, membranous, acute. Pedicel and ovary ca. 1.5 cm. Flowers spreading; sepals and petals pale pink, lip white, callus green, column white, anther cap deep purple. Dorsal sepal oblong-lanceolate, 16-20 × ca. 7 mm, 5-veined, apex acute; lateral sepals obliquely ovate-triangular, ca. as long as or slightly broader than dorsal sepal, 5-veined, apex acute; mentum jarlike, ca. 1 cm. Petals oblong, 14-18 × ca. 7 mm, 5-veined, apex acute; lip concave, cymbiform, broadly ovate when spread, 15-17 mm, claw ca. 5 mm, adaxially densely white barbellate except for claw and both sides of disk, with a square callus near base, apex abruptly contracted, recurved-caudate. Column ca. 4 mm, lower part enlarged, apex with auriculate column teeth on both sides, front densely purple crinite, foot ca. 1 cm long and wide, bent forward, inner surface sometimes sparsely hairy; anther cap nearly subglobose, densely papillate-hairy, front margin irregularly dentate, apex slightly concave.
Epiphytic on tree trunks in mountain forests; 700-1000 m. Guangdong, Guangxi, SW Guizhou, SE Hainan, NE Hunan (Taoyuan), SE Yunnan (Maguan) [Bhutan, NE India, Myanmar, Thailand, Vietnam].