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Poa glauca Vahl
Common Name: BLUEGRASS
Coefficient of Conservatism: 10
Coefficient of Wetness: 5
Wetness Index: UPL
Physiognomy: Nt P-Grass

Rock crevices and rocky shores, including the limestone areas of northern Lakes Huron and Michigan; open, sandy forests, banks, and shores.

A variable species, with shade forms often looking quite different from those of open rocks and shores. This species, P. interior, and P. nemoralis form a group distinctive (at least in our area) in the minutely pubescent or minutely warty rachilla. They are quite difficult to distinguish from each other, and a few specimens seem transitional, at least in the herbarium. Most of our problematic collections in this complex have been annotated by R. J. Soreng.

Poa glauca usually has lemmas of at least some florets with a few to many hairs between the veins near the base, and/or on the intermediate veins in contrast to the totally glabrous (between the veins) lemmas of P. interior and P. nemoralis, but this can be hard to see except with considerable magnification. Like P. interior, P. glauca has the widest glume about as wide as the lemma.

The callus at the base of the lemma may be glabrous, but in many of our specimens there is a small crinkled beard. Such specimens may be confused with P. pratensis, but differ in the generally longer glumes, pubescent rachilla, and long peduncle, as well as lacking long-creeping rhizomes. The rachilla may be nearly or quite glabrous in some specimens which also lack the beard on the callus (the beard is well developed in P. pratensis). If a node of the culm is exposed in P. glauca, it is at a point ca. 0.1–0.4 times the height of the plant. If only one node is exposed in P. pratensis, it is only slightly below the middle of the plant. Ordinarily P. glauca has a compact, purple tinged panicle (occasionally a more open greenish one) on a very long peduncle. Plants rarely approach P. nemoralis in having somewhat more leafy culms, but with long ligules.

Locations

Alger County
Alpena County
Chippewa County
    Only on Drummond Island
Crawford County
Delta County
Keweenaw County
    Including Isle Royale
Mackinac County
Marquette County
Ontonagon County
Schoolcraft County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 13, 2017. http://www.michiganflora.net/species.aspx?id=2196.