Description from Flora of China
Herbs erect, annual or perennial. Leaves petiolate, dentate. Verticillasters many flowered, crowded, into a terminal or widely spaced capitula along branches; floral leaves similar, smaller, brightly colored; bracteoles minute. Calyx tubular, elongated, straight to slightly curved, 15-veined, throat villous or hirsute; teeth 5, subequal. Corolla red, purple, white, gray, or yellow, spotted, 2-lipped, tube slightly dilated at throat; upper lip narrow, erect to arcuate, apex entire to emarginate; lower lip spreading, 3-lobed, middle lobe largest, emarginate. Anterior stamens fertile, inserted on apical part of corolla tube, exserted; posterior stamens rudimentary, minute, or absent; filaments edentate; anthers linear, versatile, cells 2, divaricate, apex confluent. Style apex 2-cleft, lobes subulate, subequal. Nutlets smooth.
About 6-12 species: North America, two species cultivated as ornamentals in China.