A perennial with a stout rootstock sheathed in basal brown scales. Leaves 7-24 x 1.6-7 cm, elliptic-obtuse or oblanceolate, margin crenulate to denticulate or sometimes dentate, glabrous to sparsely pubescent, farinose on the undersurface (farina bright yellow) or not, membranous. Scape solitary, rarely more, stout, 10-14 cm long, glabrous, except at the base of the bracts where it is farinose. Bracts 6-14 mm, lanceolate. Pedicel 11-42 mm long, exceeding the bracts. Flowers heteromorphic, umbellate, sometimes superposed. Calyx 5-11 mm long, campanulate, green or blackish in colour, farinose within, c. ½ cleft; lobes lanceolate or ovate-lanceolate. Corolla tube 11-14 mm long, limb 12.5-22 mm broad, throat yellow or white; lobes 7.5-9 x 6.5-8 mm, obovate or suborbicular, entire. Style 3-4 mm long (in thrum-eyed flowers), 10-11 mm in the pin-eyed ones. Capsule oblong, cylindric, included in the calyx. Seeds c. 1 mm long.