Plants perennial; cespitose or not, sometimes rhizomatous. Culms 10-250 cm, usually erect. Sheaths glabrous or ciliate; auricles 0.2-1.5 mm or absent; ligules membranous; blades convolute or flat. Inflorescences terminal, distichous spikes, usually not disarticulating at maturity; middle internodes 7-30 mm; disarticulation usually beneath the florets and tardy, occasionally in the rachises. Spikelets 1-3 times the length of the middle internodes, solitary, appressed to ascending, often trullate and arching outwards at maturity. Glumes oblong to lanceolate, stiff, indurate to coriaceous, glabrous or with hairs, keeled or rounded at the base, usually more strongly keeled distally than below, margins often with a hyaline margin, apices truncate to acute, sometimes mucronate, unawned, without lateral teeth; lemmas 5-veined, coriaceous, glabrous or with hairs, truncate, obtuse, or acute, sometimes mucronate or awned, awns to 3 cm; anthers 3, 2.5-12 mm. x = 7. Name from the Greek thino, a shore weed, and pyros, wheat.