黄花石斛 huang hua shi hu

Callista dixantha (H. G. Reichenbach) Kuntze.

Stems erect or pendulous, cylindric, 50-100 cm, slender, 3-6 mm in diam., unbranched, deciduous, with many nodes, internodes 2.5-3 cm, with many longitudinal ridges, pale yellow when dry. Leaves ovate-lanceolate, 8-11(-13) × ca. 1 cm, leathery, base with clasping sheath, apex long acuminate. Inflorescences often 2-4, from old leafless stems, 2-5-flowered; peduncle 1-2 cm, slender; basal sheaths 2 or 3, short, membranous; floral bracts ovate, ca. 2 mm, membranous, acute. Pedicel and ovary ca. 2 cm, slender. Flowers spreading, thinly textured, deep yellow, lip with purplish red stripes on either side at base. Dorsal sepal oblong-lanceolate, ca. 23 × 6 mm, 5-veined, apex acute; lateral sepals equal in size to dorsal sepal, base slightly oblique; mentum subcylindric, ca. 4 mm. Petals suboblong, ca. 23 × 10 mm, 5-veined, base contracted, margin irregularly denticulate, apex acute; lip suborbicular, ca. 22 × 25 mm, adaxially densely barbellate, margin erose, apex emarginate. Column very short, ca. 5 mm, foot ca. 4 mm; anther cap conic, densely finely papillate, front margin irregularly dentate, apex obtuse. Capsule narrowly cylindric, 6-7 × 0.5-0.6 cm, with a stalk ca. 1 cm.

Epiphytic on tree trunks in mountain forests; 800-1200 m. S Yunnan [Laos, Myanmar, Thailand].

This species was misidentified by S. C. Chen and Z. H. Tsi (Orchids China, 156. 1998) as Dendrobium moulmeinense (a synonym of D. devonianum in the present treatment).