Trees, shrubs or annual or perennial herbs, usually with square stems. Stipules 0. Leaves opposite or whorled, rarely alternate (e.g. Aeollanthus subacaulis), usually gland-dotted and aromatic. Infl. cymose, borne in the axils of opposite bracts, usually much condensed so that the two opposite cymes form a whorl-like infl. (referred to as a whorl in this account); rarely the flowers are solitary in the axil of each bract. The whorls are often close together so that they form spikes or heads. Flowers hypogynous, zygomorphic, usually 2-lipped, bisexual (unisexual in Tetradenia). Bracts present. Calyx usually 5-toothed, often 2-lipped. Corolla gamopetalous, basically 5-lobed but often 2-lipped with the 2 upper lobes and the 3 lower lobes united. Stamens rarely 2, usually 4. Ovary superior, 4-locular; style often 2-lobed, usually gynobasic. Fruit consisting of 4 dry, 1-seeded nutlets.