Perennial or annual herbs, conspicuously or obscurely gland-dotted. Leaves opposite or whorled, simple, sessile or petiolate, often joined across at nodes. Inflorescences a single flower or of racemes with flowers single in the axils of leaf-like bracts; bracteoles absent. Calyx-tube 5-angled, shortly 5-toothed; corolla 5-lobed, more or less rotate or 2-lipped, tube symmetrical at base, neither swollen nor spurred, upper lip 2-lobed, lower 3-lobed, longer, with a palate; stamens 4, in pairs of unequal length, filaments not spurred, anthers of each pair joined, with 2 confluent but divergent locules, staminodes absent; stigma with 2 broad equal flaps, receptive on the inner surface and irritable, closing together when touched. Capsule loculicidal, included in enlarged calyx; septa united to the 2 valves and to the central column; seeds many, not winged.
7 species from America, Australia, New Zealand, eastern Asia, India, and southern Africa, 3 species in Australia. Previously treatments included c. 100 species in this genus, most of which are now treated in segregate genera. Species in Victoria previously included in Mimulus (except for M. gracilis) are now included in Erythranthe, Elacholoma and Thyridia.