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Reed Mannagrass (Glyceria maxima)
Grass Family (Poaceae)
Reed mannagrass (also know as reed meadow grass, reed sweetgrass) is a perennial rhizomatous grass native to northern Eurasia. It can grow over 8 feet in height and occurs in freshwater marshes. The inflorescence is an erect, many-stemmed panicle 6-12 inches in height. The leaves are flat or slightly folded, 8-12 inches in length and 0.75 inches wide. The leaves are shallowly grooved along the midrib, and have short, stiff hairs at the margins. The lower parts of the stems are often reddish.
The plant spreads by seed and by rhizomes.
The native American mannagrass (Glyceria grandis), which also occurs in freshwater marshes, is similar in appearance. American mannagrass is shorter (5 feet in height), has a drooping inflorescence, and has smooth sheaths at the base of the inflorescence. Reed mannagrass has rough sheaths.
Reed mannagrass can form massive infestations in freshwater wetlands, displacing native wetland species. According to the King County, Washington description, reed mannagrass“is an inferior food and nesting source for waterfowl compared with the species it displaces and it also changes the macroinvertebrate community structure, which can impact the food chain for fish and wildlife.
Reed mannagrass has been reported in Alaska, the State of Washington, and Wisconsin as well as in Massachusetts, where it is known to be found in floodplains along the Ipswich River.
Sources and Links:
Invasive Plant Atlas of New England (IPANE)
Global Invasive Species Database: Glyceria maxima
Noxious Weeds: King County, WA—Reed sweetgrass (Glyceria maxima)
UCONN: Glyceria maxima (C.Hartm) Holmb (Reed sweetgrass)