A perennial 16-36 cm tall with a short rhizome. Leaves 8.5-22.5 x 0.5-2.3 cm, lanceolate to oblanceolate, ± firm, entire to denticulate or crenulate, often with white farina on the margin on the under surface; lateral nerves faint, base attenuate. Petiole winged. Scape 12-23 cm long, up to 31 cm in fruit, glabrous, puberulous just below the inflorescence, 11-20-flowered. Bracts 1.2-1.7 cm long, minutely pubescent, often blackish (in dried state). Pedicel exceeding the bracts, up to 4.2 cm long in fruit, puberulous. Flowers heteromorphic, yellow. Calyx 8-10 mm long, campanulate-tubular, ½ cleft, sometimes white farinose within; lobes 5-6 mm long, lanceolate, dark coloured, minutely pubescent. Corolla tube 10-12 mm long, c. 1½ times the calyx length; limb 18-21 mm broad, throat barely annulate, lobes entire to subentire, oblong-ovate to suborbicular, 6.5-8 mm long. Anthers narrow oblong. Ovary subglobose, style 2.5-3.5 mm long (in thrum-eyed flowers) to 8 mm. Capsule -cylindric, 11.5-18 mm long, exceeding the calyx. Seeds. subglobose to ovaloid, 1.5-2 mm long, brownish, papillose.