Benthamia glaberrima (Ridl.) H.Perrier, Bull. Soc. Bot. France 81: 28 (1934).
Holothrix glaberrima Ridl., J. Linn. Soc., Bot. 22: 125 (1886).
Peristylus glaberrimus (Ridl.) Rolfe, Orchid Rev. 7: 4 (1899).
Platanthera glaberrima (Ridl.) Kraenzl., Orchid. Gen. Sp. 1: 609 (1899).
Habenaria glaberrima (Ridl.) Schltr., Beih. Bot. Centralbl. 33(2): 405 (1915).
Rolfeella glaberrima (Ridl.) Schltr., Repert. Spec. Nov. Regni Veg. Beih. 33: 19 (1924).
Plants terrestrial, 30-60 cm, tall; tubers fasciculate, oblong-fusiform; stem with a single radical leaf, covered above with acuminate sheaths. Leaf narrowly lanceolate-acute, slightly gradually attenuate toward the base. Rachis densely many flowered, unilateral; bracts lanceolate, longly acuminate, generally longer than the flower; flowers small, of a sulfur yellow. Sepals narrowly lingulate, slightly joined basally with the petals. Petals lanceolate, slightly longer than the sepals. Labellum of an oval contour, obviously trilobed, with the extreme base joined to the petals; median lobe oval-acute, laterals much smaller; spur filiform, pendent, slightly longer than the pedicel. Column straight; anther obtuse or subapiculate, staminodes small, rounded; pollina claviform, cauda very short; rostellum small, tridentate. Pedicel slightly twisted.
This species is very much like Benthamia madagascariensis, differentiated by the sulfur yellow flowers and the elongated-cylindrical spur.
C. & NE. Madagascar