Herbaceous or ± slightly woody perennials; rhizomatous, or roots fleshy or tuberous. Stems erect, ± climbing, or twining, leafy. Leaves alternate, petiole usually twisted to reverse leaf-surfaces. Flowers ± actinomorphic, bisexual, in few-to many-flowered terminal umbellate inflorescences, rarely solitary, surrounded by a whorl of bract-like leaves; perianth-segments 6, petaloid, free, clawed, in 2 similar or dissimilar whorls. Stamens 6; filaments free; anthers basifixed. Ovary inferior, 3- or 1-locular; style filiform; stigma shortly 3-lobed; ovules many. Fruit a loculicidal capsule. Seeds many. Genera 4, of Central and S. America.