Phragmites australis subsp. americanus
American reedgrass (common reed)
Poaceae (Grass family)

Introduction to Vascular Plants


© Ryan Batten     (Photo ID #66768)


E-Flora BC Static Map

Distribution of Phragmites australis subsp. americanus
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The genus Phragmites is one of the most widely distributed genera in the world (Allred 2010) and is found across most of North America, excluding the Yukon, Alaska, Labrador, and Nunavut (USDA 2010). This is an easily recognized genus of tall (to 3 m), rhizomatous or stoloniferous grasses that form dense stands in saline or freshwater wetlands, including cattail marshes, sloughs, ponds and ditches. The taxonomy of the genus is not yet clear. However, in BC, two subspecies are now recognized. These are:

1) the introduced Phragmites australis subsp. australis (European common reed), an aggressive, invasive subspecies of European origin that is present along the Atlantic coast (where it is invading saltmarshes) and in several locations in British Columbia (Snyder 2009, Martin 2003, Lomer pers. comm. 2011, Brown pers. comm. 2011, Marr pers. comm. 2011). These include Vernon, Osoyoos, Richmond, Burnaby, Galiano Island and Metchosin.

2) the native Phragmites australis subsp. americanus, native to fens, bogs and river shores within its North American range (Catling 2005) and more widespread in BC.

The two subspecies are separated on the basis of glume length, culm/stem colour, leaf colour, and habitat. Identification is based on a collection of characters. See the identification section below for more details.

Populations of the native subspecies in eastern North America are reported as declining, while populations of the introduced subspecies are spreading throughout North America--this is a successful estuarine invader (Myerson 2009). Research on Phragmites shows that "the native type is a low-nutrient specialist, with a more efficient photosynthetic mechanisms and lower N demand, whereas the introduced type requires nearly four times more nitrogen than the native type to be an effective competitor" (Mozdzer and Zieman 2010). This suggests that anthropogenic modification of wetlands has provided the conditions necessary for success of the introduced type in some regions. Hybridization between the two subspecies is not widely reported but has been demonstrated through hand-pollination by Myerson et al. (2009).

Visit the Canadian Phragmites database.

Species Information

Perennial, tufted grass from fibrous roots, semi-rhizomatous; stems stout, erect, 200-300 cm tall.
Sheaths smooth, loose, twisting in the wind and aligning the blades on one side; blades flat, mostly 20-40 cm long, 10-40 mm wide, usually breaking from the stems by winter; ligules half membrane and half hairs, the innovations mostly membranous, the fringe of hairs late in developing, 1.5-3 mm long.
Inflorescence a large feathery panicle, 15-35 cm long, often purplish, but later straw-coloured; spikelets generally 3- to 6-flowered, 10-15 mm long; lower glumes 4-6 mm long, the upper ones about 6-9 mm long; lower lemmas hairy, unawned, 9-12 mm long, the upper ones generally smaller but with awns often as long as the bodies, smooth, but exceeded by the silky hairs of the rachillas; paleas scarcely half as long as the lemmas; lodicules scarcely 1 mm long; anthers about 2 mm long.

SourceThe Illustrated Flora of British Columbia

Habitat and Range

Marshes, ponds, lakeshores and ditches in the lowland, steppe and montane zones; infrequent in S and NE BC; circumpolar, N to SW NT, E to NF and NS and S to IN, LA, TX and MX; Eurasia, Trinidad, C America.

SourceThe Illustrated Flora of British Columbia


Allred, Kelly W. 2010. Phragmites revised treatment. Flora North America. Available Online.

Blossey, B. 2002. Replacement of native North American Phragmites australis by introduced invasive genotypes.BEN - Botanical Electronic News 284

Catling, P. M. 2005. New "top of the list" invasive plants of natural habitats in Canada. BEN - Botanical Electronic News 345.

Catling, P. M. 2007. Canadian Phragmites database – notes for use. BEN - Botanical Electronic News 370

Martin, M. 2003. Common Reed (Phragmites australis) in the Okanagan Valley, British Columbia, Canada. BEN - Botanical Electronic News 318

Myerson, Laura A., David V. Viola and Rebecca N. Brown. 2009. Hybridization of invasive Phragmites australis with a native subspecies in North America. Biological Invasions 12 (1): 103-111.

Mozdzer, Thomas J. and Joseph C. Zieman. 2010. Ecophysiological differences between genetic lineages facilitate the invasion of non-native Phragmites australis in North American Atlantic coast wetlands. Journal of Ecology 98 (2): 451 - 458.

Snyder, Eric. 2009. Invasive common reed (Phragmites australis (Cav.) Trin. ex Steud subsp. australis): first record for Manitoba and the Canadian prairies. Botanical Electronic News #418, December 3, 2009.

USDA. 2010. Plant profile for Phragmites australis. United States Department of Agriculture. Available Online.