They are erect plants, usually with long tap roots. The fleshy to leathery leaves form a basal rosette at the root. The basal leaves may be different from those near the inflorescence. They may or may not have stipules. There are minor leaf veins. The leaf blade margins are entire or crenate.
The usually inconspicuous flowers are carried above the leaves in clusters. The fertile flowers are mostly hermaphrodite, or they may be functionally male or female. The flowers and seeds grow on long clusters at the top of a stalk emerging from the basal rosette; in many species the flowers are green, but in some (such as sheep's sorrel, Rumex acetosella) the flowers and their stems may be brick-red. Each seed is a 3-sided achene, often with a round tubercle on one or all three sides.