Annual to perennial glabrous herbs. Leaves flat, entire. Inflorescence spike- or panicle-like with flowers sessile, solitary or in small clusters, each flower or cluster subtended by a bract and a pair of bracteoles; flowers bisexual; perianth 5-lobed in upper half, tubular and connate with ovary in lower part; stamens 5; stigmas 2 or 3. Fruit often adhering together by the swollen receptacle and perianth segments; seed horizontal, testa crustaceous.
About 7 species of Europe and Asia, 1 naturalised in Australia.