Slender, erect or ascending herb with 1-3 annual stems, up to 35 cm tall, growing from a perennial, fleshy tuberous rootstock. Stems with milky sap mostly unbranched, minutely pubescent with white spreading hairs. Leaves opposite, sessile, narrowly linear up to 10 cm long with short stiff hairs on both surfaces; margin entire, distinctly rolled under. Flowers in terminal or extra-axillary, 3-6-flowered umbels. Corolla lobes spreading or slightly reflexed greenish or greyish-purple outside, white flushed with purple or maroon on the inside, sweetly scented. Corona lobes creamy-white, fading yellowish, outer lobes spreading with the tips typically curved up forming small hoods. Fruit a single follicle up to 8 × 0.8 cm, narrowly fusiform, smooth, minutely velvety.