Flora of North America species comparison

Agrostis stolonifera grows in areas that are often temporarily flooded, such as lakesides, marshes, salt marshes, lawns, and damp fields, as well as moist meadows, forest openings, and along streams. It will also colonize disturbed sites such as ditches, clearcuts, and overgrazed pastures. Its North American range extends from the subarctic into Mexico, mostly at low to middle elevations.

Agrostis stolonifera has been confused with A. gigantea (see previous). It is considered to be Eurasian, but some northern salt marsh and lakeside populations may be native. Agrostis stolonifera is also similar to A. castellana (p. 639); it differs in having longer, acute to truncate ligules that are longer than wide, and in possessing extensive stolons. The names A. palustris Huds. and A. maritima Lam. have been applied to plants with longer stolons; all forms intergrade. A hybrid between A. stolonifera and Polypogon monspeliensis, xAgropogon lutosus (p. 668), has been found in the Flora region. It differs from A. stolonifera in having awned glumes and lemmas. Agrostis stolonifera readily hybridizes with A. vinealis (see below), the hybrids being somewhat intermediate between the two parents.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Agrostis scabra grows in a wide variety of habitats, including grasslands, meadows, shrublands, woodlands, marshes, and stream and lake margins, as well as disturbed sites such as roadsides, ditches, and abandoned pastures. It occurs throughout much of the Flora region, but is not common in the Canadian high arctic or the southeastern United States. It extends south into Mexico; it is also native to the Pacific coast from Kamchatka to Japan and Korea, and has been introduced elsewhere.

Plants in the Agrostis scabra aggregate are variable. Awned and unawned plants often occur together, the difference presumably being caused by a single gene. At least three groups may be distinguished within the species as treated here: widespread, lowland, rather weedy plants capable of producing very large panicles that have been introduced into the southern United States; smaller, short-leaved, slow-growing plants of rocks and screes, which are widespread in the Rockies, the Appalachians, and much of Alaska, Canada, and Greenland; and luxuriant, broad-leaved plants that are characteristically found in sheltered, frost-free canyons of the southwestern United States. The second group has sometimes been called A. scabra var. geminata (Trin.) Swallen or A. geminata Trin.

Tercek et al. (2003) found that annual forms of Agrostis scabra with inflated upper sheaths and open panicles that were collected around hot springs in western North America were molecularly, and in some respects morphologically, more similar to plants identified as hot spring endemics such as A. rossiae and A. pauzbetica Prob., than they were to neighboring perennial plants of A. scabra that did not have inflated leaf sheaths. They differed, however, in having open, rather than contracted, panicles.

Agrostis scabra is often confused with a number of other species; for comparisons, see under the appropriate species description: A. mertensii (p. 644), A. clavata (see previous), A. hyemalis (see next), A. perennans (see this page), and A. idahoensis (p. 649).

(Discussion copyrighted by Flora of North America; reprinted with permission.)