长苏石斛 chang su shi hu

Callista brymeriana (H. G. Reichenbach) Kuntze.

Stems erect or decumbent, usually 20-30 cm, often with 2 internodes dilated at middle and fusiform, to 11 mm in diam., base and upper part 3-5 mm in diam., unbranched, with several nodes, internodes 2.5-3 cm, ± longitudinally ridged, pale yellow tinged with dirty black when dry. Leaves often 3-5, on upper part of stem, narrowly oblong, 7-13.5 × 1.2-2.2 cm, leathery, base slightly contracted and with clasping sheath, apex acuminate. Inflorescence a raceme arising laterally on leafless previous year’s stem, suberect, 1- or 2-flowered; peduncle 1-4 cm; basal sheaths 4 or 5, overlapping, shortly tubular, membranous, basal ones shortest, ca. 2 mm, longer distally; floral bracts ovate-lanceolate, 7-12 mm, membranous, apex subobtuse. Pedicel and ovary to 5 cm. Flowers spreading, slightly thickly textured, golden yellow; column yellow, white on upper sides; anther cap pale yellowish white. Dorsal sepal oblong-lanceolate, ca. 25 × 8 mm, 7-veined, obtuse; lateral sepals sublanceolate, ca. 25 × 8 mm, base oblique, apex acute; mentum ca. 3 mm, shortly obtuse. Petals oblong, ca. 25 × 7 mm, 7-veined, entire, obtuse; lip ovate-triangular, ca. 20 × 15 mm, adaxially densely pubescent, base shortly clawed, margin shortly fimbriate below middle, above middle (especially at apex) with long and branched fringes, apical fringe longer than lip, apex slightly obtuse. Column ca. 3 mm; anther cap narrowly conic, ca. 5 mm, densely finely papillate, front margin slightly irregular. Capsule narrowly cylindric, ca. 1.7 × 1 cm, 6-ribbed.

Epiphytic on tree trunks at forest margins; 1100-1900 m. S Yunnan [Laos, Myanmar, N Thailand, N Vietnam].