Habenaria siamensis Schlechter, Repert. Spec. Nov. Regni Veg. 2: 82. 1906.中泰玉凤花 zhong tai yu feng hua

Plants 14-16 cm tall. Tubers oblong, 2-3 cm × 8-10 mm, fleshy. Stem erect, terete, 2-3 mm in diam., glabrous, often with 2 spreading basal leaves, with 3-5 bractlike leaves above. Leaf blade ovate or ovate-oblong, 4-4.5 × 2.5-3.5 cm, base amplexicaul-sheathing, apex acute or acuminate. Raceme several to more than 10-flowered, erect or arching, 4-6 cm; floral bracts lanceolate, ca. 13 mm, shorter than ovary, margin finely ciliate, apex acuminate; ovary twisted, slightly arching, cylindric, including pedicel to 15 mm, glabrous. Flowers white. Sepals 3-veined, margin finely ciliate; dorsal sepal forming a hood with petals, erect, ovate, concave, ca. 8 × 4 mm; lateral sepals reflexed, obliquely ovate-lanceolate, ca. 9 × 4 mm. Petals obliquely falcate-lanceolate, ca. 8 × 2.5 mm, 2-veined; lip spurred at base, deeply 3-lobed above base; lateral lobes linear-filiform, ± curved, 17-21 × ca. 0.5 mm, attenuate toward apex; mid-lobe straight, linear, 6-9 × 0.8-1.5 mm; spur pendulous, cylindric-clavate, 9-10 mm, conspicuously shorter than ovary, dilated from middle to end, near end ca. 2.2 mm in diam., apex obtuse; connective narrow, ca. 1 mm wide; rostellum short; stigmas oblong-clavate, ca. 4 mm. Fl. Aug.

Grassy slopes; ca. 600 m. SE Guizhou [Thailand].