杯鞘石斛 bei qiao shi hu

Callista boxallii (H. G. Reichenbach) Kuntze; C. gratiosissima (H. G. Reichenbach) Kuntze; Dendrobium boxallii H. G. Reichenbach; D. bullerianum Bateman.

Stems pendulous, cylindric, to 50 cm, ca. 5 mm in diam., fleshy, with many swollen nodes, upper part ± upcurved, internodes 2-2.5 cm, pale yellow when dry. Leaves oblong, 8-11 × 1.5-1.8(or more) cm, leathery, base with clasping sheath, apex slightly obtuse and hooked on one side; leaf sheath papery when dry, sheath mouth open cupular. Inflorescence on old leafless stems, 1- or 2-flowered; peduncle 3-5 mm; basal sheaths 2 or 3, pale white when dry, broadly ovate, 3-5 mm, papery, obtuse; floral bracts broadly ovate, 7-10 mm, papery, apex obtuse. Pedicel and ovary pale purple, ca. 2 cm. Flowers fragrant, spreading, papery; sepals and petals white with pale purple tips, lip with many purplish red stripes on each side, disk with a pale yellow transverse semilunar central blotch, column white, front side with purple stripes, anther cap white. Dorsal sepal ovate-lanceolate, 23-25 × 7-8(or more) mm, 7-veined, apex acute or slightly obtuse; lateral sepals suborbicular, equal in size, 7-veined, base oblique, apex acute; mentum subglobose, small, ca. 3 mm. Petals obliquely ovate, 23-25 × 13-14 mm, main veins 5, secondary veins many, base contracted into a short claw, margin entire, apex obtuse; lip nearly broadly obovate, ca. 23 × 20 mm, adaxially densely barbellate, base cuneate, margin ciliate, apex rounded. Column ca. 4 mm; anther cap subconic, densely finely papillate, front margin irregularly dentate. Capsule ovoid, ca. 3 × 1.3-1.6 cm.

Epiphytic on tree trunks in open forests; 800-1700 m. S Yunnan [NE India, Laos, Myanmar, N Thailand, Vietnam].