反瓣石斛 fan ban shi hu

Distichorchis ellipsophylla (Tang & F. T. Wang) M. A. Clements.

Stems erect or ascending, cylindric, ca. 50 cm, ca. 5 mm in diam., uniformly thick, with longitudinal ribs, unbranched, with many nodes, internodes ca. 2 cm, enclosed in leaf sheaths. Leaves alternate and dense along whole stem, elliptic, 4-5 × 1.5-1.9(or more) cm, base cordate, clasping and decurrent into sheaths tightly embracing stem, apex obtuse and unequally 2-lobed. Inflorescences many, (apparently) leaf-opposed, 1-flowered; floral bracts small. Pedicel and ovary bent downward, ca. 2 cm, slender. Flowers scented, white, disk yellow above middle, keels brownish purple. Dorsal sepal reflexed, ovate-oblong, ca. 8 × 5 mm, apex acute; lateral sepals reflexed, oblong-lanceolate, ca. 8 × 5 mm, apex acute; mentum angulate, ca. 7 mm. Petals recurved, narrowly lanceolate, ca. 7 × 4 mm, apex acute; lip larger than sepals, fleshy, 3-lobed, ± decurved and folded along axis; lateral lobes deltoid, small, ca. 2 mm, acute; mid-lobe nearly transversely oblong or rounded, somewhat large, ca. 10 × 15 mm, subtruncate and broadly emarginate, central part of disk with 3 keeled ridges.

Epiphytic on tree trunks in broad-leaved mountain forests; ca. 1100 m. SE Yunnan (Menghai, Mengla) [Cambodia, Laos, Myanmar, Thailand, Vietnam].

This species was misidentified by Z. H. Tsi (Acta Phytotax. Sin. 18: 434. 1980) as Dendrobium revolutum Lindley.