Coefficient of Conservatism:
Coefficient of Wetness:
R. W. Smith
Widespread in old fields, roadsides, disturbed ground, rocky or sandy forests and openings (oak, aspen, jack pine), usually in dry places but sometimes on shores and in moist forests. Introduced from Europe very early and first collected in 1838 in Washtenaw Co.
This species and P. pratensis are two of our commonest grasses. They are generally segregated from our other species of Poa by the presence of creeping rhizomes, the plants thus forming large colonies. While a useful field character, the rhizomes may not be evident on specimens merely picked or pulled hastily from the ground. Hence, the presence of rhizomes was not emphasized in the key. Poa compressa differs from P. pratensis in the flattened, less tufted culms, lemmas with obscure intermediate nerves and sparse or even absent web at the base, and a tendency toward a more slender panicle with fewer branches at each node. Elongated vegetative stems, with nodes and internodes are common in P. compressa, but in P. pratensis, vegetative shoots are short and the stem-like portion is composed of overlapping leaf sheaths.