Plants 25-55 cm tall. Rhizome somewhat dorsiventrally compressed, obliquely ovoid, ca. 2 cm in diam. Stem to ca. 8 cm, stout, 4-leaved. Leaves oblong-lanceolate, 8-35 × 1.5-2.8 cm, base contracted into amplexicaul sheath, apex acuminate or acute. Peduncle to ca. 40 cm, ebracteate; rachis flexuous, 3-8-flowered, simple or very rarely branched; floral bracts deciduous at anthesis, oblong-lanceolate, 18-20 mm, apex acute. Flowers erect or spreading, yellow; pedicel and ovary twisted, ca. 18 mm. Sepals and petals subequal in length, usually pale yellowish green, very rarely whitish, outer surface often with small purple spots, oblong, 18-23 × 5-7 mm, apex obtuse or subacute; lip ovate-elliptic, 15-20 × 8-12 mm, 3-lobed above middle; lateral lobes erect and embracing column, oblong, apex obtuse; mid-lobe subsquare, margin slightly undulate, apex emarginate; disk with 5 longitudinal lamellae extending from base of lip almost to apex of mid-lobe; lamellae undulate only on mid-lobe. Column 15-18 mm, with narrow wings. Fl. Jun-Aug.
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