Aira L.
Type species: A. praecox L.
Slender, annual or biennial, glabrous, herbaceous tufts. Leaf-sheath rounded. Ligule membranous. Leaf-blade convolute to flat, narrow. Panicle with delicate branches. Spikelets ± laterally compressed, small, 2-flowered; disarticulation above glumes and between florets; rachilla not, or occasionally, prolonged. Glumes subequal, membranous, delicate, ≈ or > lemmas, 1-3-nerved. Lemma 5-nerved, lanceolate, becoming ± chartaceous below, hyaline above, apex shortly bifid, with a fine, dorsal, geniculate awn, or the lower or both lemmas awnless. Palea < lemma, 2-keeled. Callus very short, hairy. Lodicules 2, lanceolate, acute, glabrous. Stamens 3. Ovary glabrous; styles free. Caryopsis dorsiventrally compressed, longitudinally grooved; embryo small; hilum punctiform or shortly elliptic; endosperm solid.
Key
8 spp., from temperate Europe, western Asia and North Africa. Naturalised spp. 3; transient sp. 1.