1. Didymoplexiella siamensis (Rolfe ex Downie) Seidenfaden, Bot. Tidsskr. 67: 99. 1972.
锚柱兰 mao zhu lan
Leucolena siamensis Rolfe ex Downie, Bull. Misc. Inform. Kew 1925: 416. 1925.
Plants slender, 8-30 cm tall. Rhizome brown, fusiform, 8-24 mm, 3-5 mm in diam.; roots few, wiry, often with small globose thickenings. Stem 7-28 cm, with 2 or 3 scalelike sheaths, brown. Rachis 0.2-3 cm, elongating in fruit, slightly dilated, laxly to subdensely 3-20-flowered; floral bracts ovate, ca. 2 mm, apex acute. Flowers white, sometimes tinged pink, campanulate; pedicel and ovary erect or spreading, brown, 0.4-1.4 cm; pedicel extending to ca. 2 cm in fruit. Dorsal sepal and petals 5-7 mm, united for 1/2 of their length, free portion ovate, shallowly 3-lobed, each lobe ovate-deltoid and with an acute apex; lateral sepals 5-8 mm, connate with each other for ca. 2/3 of their length, and with petals only at their base, free portion 2-lobed, each lobe ovate, oblique and with an acute apex, reflexed; lip cuneate-spatulate, 5-6 × 2-3 mm, apex truncate and emarginate, midvein raised on disk and with irregular calli at apex, with small glands at base. Column elongate, ca. 4 mm, dilated toward apex, column wings triangular and extending into decurved stelidia; each stelidium ca. 2 mm; anther orbicular and borne on distinct filament; rostellum thickened. Capsule cylindric, ca. 2.2 cm. Fl. Apr-Jul. 2n = 36, 150.
Shaded places in broad-leaved forests. S Hainan, S Taiwan [Japan (Ryukyu Islands), Thailand, Vietnam].