Agrostis gigantea

History of Spread

Agrostis gigantea (Redtop) is a Eurasian grass, widely cultivated for lawns and pastures, and extensively naturalized in 'moist meadows, shores, and coastal marshes' (Gleason and Cronquist 1991). In this account, we assume that records of 'A. alba' from 1814 onwards (Pursh 1814; Fernald 1950; Hitchcock and Chase 1950), and given the common name of 'Redtop' refer to the presently recognized taxon. There is some uncertainty about the identity of these early records. Some of them may refer to A. stolonifera, (of which A. gigantea has been treated as a variety) which may have both introduced and native strains in North America. 'A. alba' was widespread in northeastern North America by 1814 (Pursh 1814). In North America, it prefers cooler climates, but is established from Canada and Alaska to Mexico (Hitchcock and Chase 1950; Natural Resource Conservation Service 1998). Agrostis gigantea has a preference for moist soils, and is known from fresh and brackish tidal marshes (Fernald 1950; Gleason and Cronquist 1991).

In local floras and species lists, where the name 'A. alba' is used, it is often uncertain whether A. stolonifera or A. gigantea is referred to, so we have relatively few specific tidal records of this widespread grass. It has been reported from a freshwater tidal marsh on the Merrimack River MA (Caldwell and Crow 1992), from the upland borders of salt marshes on Fire Island (Great South Bay) NY, and from shores of Barnegat Bay (Small and Gillis 1980), the Great Lakes (Dore and Michel 1980; Mills et al. 1993), and fresh-brackish marshes of the Columbia River (Thomas 1984). In the Chesapeake Bay watershed, 'A. gigantea is widespread (Brown and Brown 1984; Harvill et al. 1992; Natural Resources Conservation Service 2002; Rhoads and Klein 1993), occurring in portions of the watershed in VA; DC; MD; DE; WV; PA, and probably in NY. It probably occurs in tidal marshes, but local records do not provide sufficient descriptions of habitat to verify its occurrence within our study area. Most specimens in the U.S. National herbarium came from 'vacant lots' and 'meadows', but a number came from locations near tidal waters. From 1873-1895, several specimens were collected from the 'Eastern Branch' (Anacostia River). In 1989, 2 sets of specimens were collected from 'lawn edges' or 'riverwalls' along the Potomac and Anacostia Rivers, respectively. Additional herbarium specimens were collected on shores of the middle Bay (Drum Point, Calvert County MD, 1986), the Potomac estuary (Rocks Point, Charles County MD 1921) (U. S. National Herbarium collections) . Published reports include: (as 'A. alba) 'upper margins' of upper Chesapeake Bay (Kent County, Krauss et al. 1971); (as A. stolonifera major) nontidal fresh-brackish impoundments on Assateague Island/MD-VA (Hill 1986); (as A. gigantea), 'Fields, ponds, swamps' in King George County VA (Simmons et al. 1995).

References- Brown and Brown 1984; Caldwell and Crow 1992; Dore and Michel 1980; Harvill et al. 1992; Hill 1986; Fernald 1950; Gleason and Cronquist 1991; Hitchcock and Chase 1950; Krauss et al. 1971; Mills et al. 1993; Pursh 1814; Simmons et al. 1995; Small and Gillis 1980; Thomas 1984; Natural Resource Conservation Service 1998; U. S. National Herbarium collections

Invasion Comments