Plants rhizomatous. Culms 10-120 cm, glabrous, lowest internode plus sheath 2-3 mm thick. Lower sheaths ciliate; auricles absent or to 0.5 mm; ligules 0.3-0.6 mm, truncate, ciliate; blades to 35 cm long, 2-6 mm wide, flat or convolute, glaucous, adaxial surfaces 3-20-ribbed, ribs prominent, crowded, flattened, scabrous. Spikes 4-10 cm; rachises glabrous, not disarticulating at maturity. Spikelets 10-20 mm, with 3-10 florets. Glumes 8-10 mm, glabrous, oblong-lanceolate, 4-7-veined, keeled, keels asymmetric, scabridulous, midveins slightly longer and more prominent than the lateral veins, apices acute; lemmas 7-11 mm, glabrous, subobtuse, unawned, mucronate, or awned, awns to 10 mm; paleas keeled, keels ciliate; anthers 5-7 mm. 2n = 42.
Thinopyrum pycnanthum is native to the coasts of western and southern Europe. It is reported from scattered locations in the western United States and from Nova Scotia to New Jersey in eastern North America. In its native range, it grows in maritime sands and gravels or river gravels.