Aquatic or semi-aquatic rhizomatous perennials. Leaf-blades linear, often inrolled; ligule membranous. Inflorescence open, composed of several to numerous racemes scattered along a central axis; racemes slender, straight or flexuous, secund. Spikelets several-flowered, narrow, acuminate, often rounded, biseriate, subsessile or shortly pedicelled, disarticulating between the florets; glumes 1-nerved, persistent, membranous, unequal, shorter than the lemmas; lemmas 3-nerved, rounded or flattened on the back, hairy or rarely almost glabrous on the lower part of the nerves, usually 2-toothed, mucronate or shortly awned; palea scabrid on the keels and appressed sericeous on the inturned margins. Caryopsis elliptic-oblong, plump or dorso-ventrally flattened.