Description from Flora of China
Plants annual [rarely perennial]. Culms usually erect. Spike distichous, very dense; rachis usually very brittle, pubescent. Spikelets 1 per node, sessile, with 2 florets, occasionally with rudimentary 3rd floret. Glumes linear-subulate, keeled, hispid along keel, margin membranous, apex acuminate or awned. Lemma lanceolate, asymmetric, 5-veined with 2 marginal veins forming keels, hispid along keels, apex acuminate or tapering into long, straight, scabrous awn. Palea equaling lemma, smooth or scabrous along keels or ciliate distally, apex 2-dentate. Lodicules ciliate distally. Caryopsis oblong, somewhat laterally compressed, deeply furrowed, apex pubescent. x = 7.
About five species: mainly in temperate Europe and Asia; three species (two introduced) in China.