39. Dendrobium leptocladum Hayata, Icon. Pl. Formosan. 4: 43. 1914.
菱唇石斛 ling chun shi hu
Dendrobium tenuicaule Hayata, J. Coll. Sci. Imp. Univ. Tokyo 30(1): 316. 1911, not J. D. Hooker (1890), nor Ridley (1899); Grastidium leptocladum (Hayata) Rauschert.
Stem pendulous, narrowly cylindric, 20-50 cm, ca. 1.5 mm in diam., usually branched, internodes 1.5-2 cm. Leaves linear or grasslike, 5-10 × 2.5-5(or more) cm, base sheathing, with joint at junction with leaf blade, apex acute; leaf sheath persistent, tightly embracing stem. Inflorescence on lower part of leafless stem, 1- or 2-flowered. Pedicel and ovary 6-10 mm. Flowers half opening, snow-white. Dorsal sepal elliptic, ca. 12 × 4 mm, apex acute; lateral sepals obliquely ovate-lanceolate, ca. as long as dorsal sepal, 4-6(or more) mm, base oblique, apex acute; mentum long and narrow, ca. 4 mm. Petals narrowly elliptic, ca. 12 × 3.5 mm, apex acute; lip rhombic, 14-15 × 7-8(or more) mm, adaxial surface with curly hairs in center above middle, base contracted into a claw, margin inconspicuously 3-lobed; disk with 1 longitudinally compressed, thick central ridge. Column ca. 1 mm, foot ca. 5 mm, anther cap subrounded.
● Epiphytic on tree trunks in mountain forests, lithophytic on rocky cliffs in mountain valleys; 600-1600 m. Taiwan (Nantou, Taidong).