Terrestrial or sometimes epiphytic, acaulescent, erect, small herbs, tuberous. Stems unbranched. Leaves opposite, radicular, strongly unequal in a pair, rarely more than one pair in the wild, plant appearing as having a single leaf, foliar nectaries absent; smaller leaf mostly scale-like, very small to minute, rarely a much smaller version of the larger one. Flowers axillary, few in subcymose inflorescences; pedunculate; bracteoles small, pedicellate. Calyx lobes free; corolla pale blue or tube white and limb lavender or white with purple dots inside, broadly tubular or campanulate; stamens included, filaments not connate, anthers coherent in pairs, dehiscing by longitudinal slits, thecae parallel; staminode present; disc absent; ovary superior, stigma 2-lobed. Fruit a fleshy, becoming dry, green to light brown capsule, loculicidally dehiscent, 2-valved, valves opening to 180°.