Annual or perennial herbs. Leaves on non-flowering shoots opposite or whorled on spreading, usually prostrate stems from base of plant; leaves on flowering stems alternate and narrower; lamina simple, margins entire, sessile. Flowers in terminal bracteate racemes or spikes (rarely solitary in the axils of foliage leaves); bracteoles absent. Sepals 5, often unequal, fused only at base; corolla 2-lipped, tube cylindric with a basal spur, upper lip 2-lobed, lower lip deeply 3-lobed with palate usually closing the throat; stamens 4, in pairs of unequal length, enclosed in corolla; stigma simple or divided. Capsule more or less globose, dehiscing by vertical slits in upper half; seeds numerous.
About 120 species, from temperate Northern Hemisphere, particularly the Mediterranean region; 6 species naturalised in Australia.
Most species bear at their base short non-flowering shoots; in the annual species these may be hairy when the rest of the plant is glabrous, and bear whorled leaves which are often broader and shorter than those of the flowering stems.