Scandent or climbing herbaceous annuals or perennials with fibrous roots or tap-roots. Leaves alternate, hastate to broadly sagittate, rarely cordate, glabrous, margins entire or rarely broadly crenate, petiolate; petioles twining. Flowers solitary, axillary, pedicellate. Sepals 5, free, lanceolate; corolla 2-lipped, pink, 5-lobed, upper 2 recurved, lower 3 recurved or projecting forwards, red, blue, blue-violet or violet with whitish base; stamens 4, in pairs of unequal length, included, staminode 1, rudimentary; stigma conical, shallowly grooved. Capsule 2-valved, irregularly ovoid, triangular-ovoid or globose, loculicidal; seeds numerous, winged and minutely tuberculate or not winged and tuberculate to crested.
4 species native to Mexico and southwest U.S.A. 2 species recorded in Australia.