Herbs or subshrubs, annual or perennial. Stems erect or clambering-straggling. Leaves alternate, petiolate; blade mostly lanceolate, ovate, or deltate. Inflorescences terminal and often axillary spikes or panicles, often fasciated in cultivated forms, many-flowered. Flowers bisexual; tepals 3-5, distinct, membranous or scarious, usually glabrous; filaments connate basally into cups; anthers 4-locular; pseudostaminodes absent; ovules 3-many; style persistent, 0.2-4 mm; stigmas 2-3, capitate or subulate. Utricles ovoid, membranaceous, dehiscence centrally circumscissile. Seeds (2-)3-many, black, flattened. x = 9.