Annual or perennial herbs; glabrous, pubescent or glandular-hairy. Leaves opposite, linear; bracts more or less scarious or absent. Flowers in paniculate or more or less capitate dichasia, 5-merous, unisexual or bisexual; epicalyx present; calyx tubular, 5–15-veined, green with scarious seams between veins, 5-lobed; petals exceeding calyx; coronal scales absent; stamens 10; ovary 1-celled above, 4-celled below, with several ovules, styles 2. Capsule narrow-ovoid, opening by 4 teeth; carpophore short; seeds several, ovate-scutate, dorsiventrally compressed, tuberculate or reticulate.
About 20 species, indigenous from the Canary Islands eastwards through the Mediterranean region to Kashmir; 2 species naturalised in Australia.