USGS - science for a changing world

Northern Prairie Wildlife Research Center

  Home About NPWRC Our Science Staff Employment Contacts Common Questions About the Site

Aquatic and Wetland Vascular Plants of the Northern Great Plains

Poa L. -- Bluegrass

Tufted or rhizomatous perennials (those included here) of short to moderate stature, green or glaucous; culms erect to decumbent, hollow, sometimes compressed. Leaves mostly near the base, the blades flat to folded, the margins and midrib converging to a blunt, keeled leaf tip resembling the prow of a boat; sheaths partly closed, rounded or keeled; ligules membranous. Inflorescence an open to narrowly contracted panicle of small, mostly 2- to 8-flowered spikelets. Spikelets disarticulating above the glumes and between the florets; glumes subequal or the second a little longer than the first, acute; first glume 1- to 3-nerved; second glume 3-nerved; lemmas acute to blunt-tipped, reduced in size upward in the spikelet, faintly 5-nerved or appearing 3-nerved, with the intermediate nerves very obscure or obsolete, keeled or rounded on the back, often with a tuft of cobwebby hairs at the base, this sometimes scant, otherwise glabrous, scabrous or pubescent mainly on the nerves, sometimes pubescent or scabrous between the nerves as well; palea nearly as long as the lemma.

Lead Characteristic Go To
1 Culms strongly compressed, 2-edged; sheaths keeled. P. compressa
1 Culms round to slightly compressed, not 2-edged; sheaths rounded. Lead 2
2 Lemmas with a tuft of cobwebby hairs at the base, this sometimes scant; foliage green. Lead 3
2 Lemmas lacking a tuft of cobwebby hairs at the base, pubescent only on the keel and lateral nerves and sometimes between the nerves on the lower back; foliage glaucous. P. arida
3 Plants tufted, sometimes stoloniferous, lacking rhizomes; panicle diffuse and open (contracted when young), mostly 8-30 cm long. Lead 4
3 Plants extensively rhizomatous; panicle more compact, mostly 3-13 cm long. P. pratensis
4 Lemmas pubescent on the keel and on the marginal nerves toward the base, the intermediate nerves very fiant to obsolete. P. palustris
4 Lemmas pubescent on the keel only, not on the marginal nerves, the intermediate nerves prominent. P. trivialis

63. Poaceae, the Grass Family
23. Poa L. -- Bluegrass
1. Poa arida Vasey -- Plains bluegrass
2. Poa compressa L. -- Canada bluegrass
3. Poa palustris L. -- Fowl bluegrass
4. Poa pratensis L. -- Kentucky bluegrass
5. Poa trivialis L. -- Rough bluegrass

Return to Family -- Poaceae - The Grass Family
Return to Contents

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Webmaster
Page Last Modified: Saturday, 02-Feb-2013 06:38:43 EST
Sioux Falls, SD [sdww54]