Annual, erect or ascending, herb; leaves petiolate, opposite, ovate-lanceolate, acute, entire or crenate-serrate, 3-nerved sparsely pubescent on both surfaces; heads long peduncled, axillary or terminal, heterogamous and radiate or homogamous and disciform, solitary or in panicles; involucres ovoid or campanulate; bracts 2-seriate, ovate, acute, glabrous; ray florets female, 1-seriate, fertile, ligulate, white or yellow; disc florets bisexual, fertile, tubular, 4-5 lobed, yellow; anther bases truncate, entire or 2-toothed; style arms truncate; achenes narrowly obovate, triquetrous or compressed, margined, glabrous or scabrid; pappus usually 1-2 bristles.