Erect, branched glabrous or pubescent herbs or undershrubs. Branches alternate to opposite. Leaves opposite or verticillate, entire or toothed, gland-dotted. Flowers in groups of 1-2 (-4) in leaf axils, white, yellow or pale blue, small. Pedicels ebracteolate. Calyx divided into 4-5 imbricate, almost free segments. Corolla subrotate, 4-lobed, the lobes equal, the posterior one emarginate; throat densely bearded. Stamens 4; anthers ovoid, subsagittate at base, versatile, exserted; thecae parallel or divergent, distinct. Style pubesceent, clavate; stigma punctiform, emarginate, exserted. Capsule globose or ovoid, 2-valved, membranous, dehiscing septicidally and loculicidally from the apex. Seeds many, obovoid, angular, scrobiculate.

About 20 species, all native to the Neotropics (mainly S. America, especially Brazil, and Mexico). One species is now a widespread weed throughout both New and Old World tropics, including Pakistan and India.

In the APG III classification (2009) Scoparia is included in the expanded family Plantaginaceae.