Herbs, perennial, from fascicles of fusiform tubers. Stems mostly simple; fertile stems to 1 m or more; sterile stems shorter, more leafy. Leaves alternate; petiole often twisted so as to invert leaf; blade parallel-veined, linear to ovate, margins entire. Inflorescences terminal, umbellate [or 1-flowered]. Flowers slightly zygomorphic; tepals 6, distinct, red, orange, purple, green, or white, frequently spotted, to 5 cm; stamens 6, inserted on perianth base, declinate, usually unequal; ovary inferior; style slender; stigma 3-lobed, filiform. Fruits capsular, 3-valved, dehiscence loculicidal.
Introduced; North America, South America.
Species ca. 60 (1 in the flora).