12. Dendrobium thyrsiflorum H. G. Reichenbach ex André, Ill. Hort. 22: 88. 1875.
球花石斛 qiu hua shi hu
Callista thyrsiflora (H. G. Reichenbach ex André) M. A. Clements; Dendrobium densiflorum Wallich var. alboluteum J. D. Hooker; D. galliceanum Linden.
Stems erect or ascending, cylindric, 12-46 cm, stout, 7-16 mm in diam., base contracted and narrowly cylindric, with several nodes, with several longitudinal ridges, yellowish brown and glossy. Leaves 3 or 4 on upper part of stem, alternate, oblanceolate, 9-16 × 2.4-5 cm, leathery, base not decurrent into clasping sheaths, but narrowed into a stalk ca. 6 mm, apex acute. Inflorescence arising laterally on previous year’s leafy stem, pendulous, 10-16 cm, densely many flowered; peduncle with 3 or 4 papery basal sheaths; floral bracts pale white, obovate, 10-15 × 5-13(or more) mm, papery, with several veins, not convolute when dry, apex bluntly rounded. Pedicel and ovary with pale white stripes tinged with purple, 2.5-3 cm. Flowers spreading, thin; sepals and petals white, sometimes flushed pink especially abaxially, lip golden yellow, column white, foot pale yellow, anther cap white. Dorsal sepal ovate, ca. 15 × 8 mm, 5-veined, entire, obtuse; lateral sepals slightly obliquely ovate-lanceolate, ca. 17 × 7 mm, 5-veined, entire, obtuse; mentum subglobose, ca. 4 mm wide. Petals suborbicular, ca. 14 × 12 mm, 7-veined with many secondary veins, base with claw ca. 2 mm, margin irregularly finely toothed above base, apex bluntly rounded; lip suborbicular to triangular, ca. 15 × 19 mm, abaxially sparsely pubescent, adaxially densely pubescent, bluntly rounded, base with claw ca. 3 mm; claw ornamented with a ligulate structure; column foot ca. 4 mm; anther cap compressed, conic.
Epiphytic on tree trunks in mountain forests; 1100-1800 m. SE Yunnan [NE India, Laos, Myanmar, N Thailand, Vietnam].