Plants annual or biennial; tufted, not mat-forming. Culms 5-50 cm, erect to decumbent. Ligules 1-2 mm, obtuse to truncate, entire; blades 2-6 cm wide, flat or folded. Panicles 2-10 cm, contracted at maturity, lower branches ascending, spikelet-bearing nearly to the base; pedicels scabrous, sometimes only slightly so, sometimes with tumid epidermal cells. Spikelets 4-9 mm, with 2-6 florets. Glumes rounded to keeled over the back, midveins obscure or prominent, extending to the apices, often scabrous distally, lateral veins obscure, apices acute to obtuse; lower glumes 1-2 mm; upper glumes 2-3.2 mm; calluses with a few hairs; lemmas 2.5-4 mm, somewhat coriaceous for most of their length, glabrous or sparsely hairy on the lower 1/2, particularly along the veins, backs rounded to keeled, 5-veined, midveins and sometimes all veins prominent, midveins extending to the margin, often excurrent, apical margins hyaline, smooth to densely scabrous, apices acute to obtuse, entire; palea veins shortly ciliate proximally, shortly ciliate to scabrous distally; anthers 0.8-1.2 mm. 2n = 42.
N.Y., N.J., Pa., Wash.
Puccinellia rupestris grows in coastal and noncoastal habitats in Eurasia; North American collections were apparently introduced in ballast.