Poa sallacustris

Rhizomatous perennial, culms ascending to erect, terete to somewhat compressed, to 30 cm high. Leaves smooth and glabrous; sheath tubular in lower part; blade loosely to closely folded, firm, to 12 cm long and 2 mm wide when flattened, abruptly tapered to a keeled, acute, often slightly incurved apex; ligule thinly membranous, acute to obtuse, 1–2 mm long. Inflorescence an ovate panicle, to c. 10 cm long and 7 cm wide, the branches bare for the greater part, finally widely spreading. Spikelets 4–6-flowered, 5–8 mm long; glumes subequal, 3-nerved, equal to or slightly longer than the adjacent lemmas, smooth along keel; lemma 5-nerved, c. 3 mm long, rather firm, hairy on the keel in the lower half, and occasionally also along the lateral nerves near the base, the internerves usually glabrous; web not or weakly developed. Flowers Sep.–Dec.