Aquatic and Wetland Vascular Plants of the Northern Great Plains
63. Poaceae, the Grass Family
2. Agrostis L. -- Bentgrass3. Agrostis stolonifera L. -- Redtop
Rhizomatous or sometimes stoloniferous perennial 3-10(14) dm tall; culms erect or decumbent at the base. Leaf blades ascending, 1-6 mm wide, scabrous; sheaths glabrous, the ligule hyaline, usually splitting, 1-5 mm long. Panicle open (rarely contracted) but not diffuse, (2)6-20 cm long, the main branches branching and bearing spikelets near the base and toward the tips. Spikelets usually purplish, turning pale or whitish after anthesis; glumes ovate-lanceolate to lanceolate, acute to mucronate, 1.5-2.5 mm long; lemma 1.6-2 mm long; palea present, 1/2 to 2/3 as long as the lemma; anthers 0.5-1.3 mm long. Grain brown, ellipsoid, 0.8-1.2 mm long. Jul--Sep. Wet meadows, seepage areas, ditches, stream banks and shores; frequent to common; (Intro. from Europe and cultivated here as a pasture grass, escaped throughout most of Can. and the U.S.). A. alba L., A. gigantea Roth., A. palustris Huds.
Most northern Great Plains material fits var. major (Gaud.) Farw., a robust, predominantly rhizomatous form, sometimes producing stolons as well. More slender, weakly rhizomatous plants that reproduce freely by stolons are referred to var. stolonifera. Distinction between these two varieties is often difficult. Also occurring sporadically in our range is a form in which the panicle is narrow and contracted through maturity. Such plants are var. palustris (Huds.) Farw.
Agrostis stolonifera (from Hitchcock 1950, as A. alba). |
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