Alopecurus geniculatus var. geniculatus
Alopecurus geniculatus var. geniculatus
(water foxtail)
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Alopecurus geniculatus var. geniculatus L.

Common name: water foxtail

Synonyms and Other Names: Alopecurus geniculatus var. geniculatus; Alopecurus pallescens

Taxonomy: available through www.itis.govITIS logo

Identification: Leaves and Stem:

Stems are numerous and erect to decumbent (Klein 2011). Leaves are green to gray-green; flat (Klein 2011). The sheath is open; auricles absent (Klein 2011). The ligules extend 3–5 mm high; pointed or blunt with smooth or ragged edges (Clayton et al. 2006). The flat leaf blade surface is scaberulous; rough on the upper surface; 2–6 mm wide; 2–12 cm long (Clayton et al. 2006).

Flower-head and Flowers:

Inflorescences are pale green to purplish panicles arranged in linear spikes; 2-7 cm tall; 0.3-0.7 cm wide; cylinder shaped; tapered at end (Clayton et al. 2006, Klein 2011). Panicle axis has rounded ribs (Clayton et al. 2006).

Spikelets are solitary; 1.9-3.5 mm; ascending hairs on edges (Clayton et al. 2016). Fertile spikelets have 1 floret; oblong pedicels; rhachilla extension absent (Clayton et al. 2006, Klein 2011). Upper and lower glumes are oblong; 2.5–3.5 mm long; membranous; keeled; 3–veined with primary vein ciliate (Clayton et al. 2006). Glumes are connate at base; exceeding or reaching apex of florets; long hairs on the keel; silky hairs across the back (Clayton et al. 2006, Klein 2011). Lemma are oblong; membranous; keeled; 4 –veined (Clayton et al. 2006, Klein 2011). Lemma margins are connate below, apex truncate, 1-awned (Clayton et al. 2006). The awn is bent and attached 0.5 mm above the lemma base and extend well beyond the glumes (Klein 2011). Palea absent or minute (Clayton et al. 2006). Flower lodicules absent; 3 anthers; 1.5–2 mm long (Clayton et al. 2006, Peeters 2004). Stigmas protogynous; terminally protrude; pubescent (Clayton et al. 2006). Ovary glabrous (Clayton et al. 2006).

Other Features:

Generally, a small low grass, stems start off along the ground (Fofonoff et al. 2003). Culms decumbent; 15–45 cm long; 1–5 noded (Clayton et al. 2006). A. geniculatus can root at nodes (Klinkenberg 2010, Klein 2011). Fruit is a Caryopsis with adherent pericarp (Clayton et al. 2006).

Size: 20 to 60 cm (Klein 2011).

Native Range: Native to Eurasia, where it ranges from Northern Scandinavia to the Mediterranean, west to the Russian Pacific Coast and Western Asia (Fofonoff et al. 2003, USDA 2011). The full extent of its native range remains unknown (Kartesz 1994).

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Interactive maps: Point Distribution Maps

Nonindigenous Occurrences: Naturalized in eastern United States of America (USA); northwest USA, north-central USA, northeast USA, southwest USA, southeast USA: AK, AZ, CA, CO, CT, DC, IA, ID, IL, MA, MD, ME, MI, MN, MT, ND, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SD, TX, UT, VA, VT, WA, WI, WV, WY (USDA 2011). A. geniculatus was found among Maryland herbarium specimens collected before 1753 (Brown et al. 1987).

Naturalized in Canada in British Columbia, Alberta, Saskatchewan, Ontario, Quebec, New Brunswick, Nova Scotia, P.E.I., Newfoundland, and the Yukon since 2000 (NatureServe 2008, Cody et al. 2003).

The first reported specimens from the Great Lakes basin were collected in 1882-1886 in Lake Erie drainage (Fofonoff et al. 2003). Invasion pathways are through shipping, dry ballast, agriculture, and possibly cultivated (Fofonoff et al. 2003).

Found in 4 counties in Michigan: Alpena, Lenawee, Macomb, and Saginaw (University of Michigan: Herbarium 2016). First collected Alpena County in 1988 (University of Michigan: Herbarium 2016).

Ecology: Alopecurus geniculatus is an emergent, perennial tufted grass that grows 20-60 cm tall, adapted to moist or wet soils with a variety of textures, with a preferred substrate of wet clay, mud, silt, or peat (Clayton et al. 2006, Fofonoff et al. 2003, Klein 2011). A. geniculatus has a wetland indicator status of 'OBL' (obligate), meaning there is roughly a 100% chance of this plant occurring in wetlands (USDA 2016). Preferred habitat is non-tidal freshwater marshes, but also occasionally is found in freshwater tidal marshes (Fofonoff et al. 2003). A. geniculatus prefers full sun (Klein 2011). It is tolerant of salt and anaerobic conditions but is moderately to highly nutrient demanding and drought-intolerant (Peeters 2004, USDA 2011). It grows in shallow water, ditches, open wet meadows, shores, and stream banks from the lowland to montane zones up to 5085 ft. Northern Virginia is at the southern limit of A. geniculatus range on the East Coast (Fofonoff et al. 2003, Harvill et al. 1992, Klein 2011).

A. geniculatus reproduces sexually by seeds and can reproduce vegetatively by rooting at stem nodes (Klinkenberg 2010). The amount of seeds produced per plant and the maximum period of viability is unknown, however, seeds remain viable in the soil for at least three years (Roberts 1986). A. geniculatus is a hemicryptophyte and epibenthic, it germinates and emerges within a half inch of the soil surface (Fofonoff et al. 2003, Plant Atlas 2016). Seeds have a mass of approximately 0.8 mg (USDA 2011) and therefore can likely be transported short distances by wind. Its most active growth period is in the spring, and it flowers June-August (Peeters 2004).


Means of Introduction: Invasion pathways are through shipping, dry ballast, agriculture, and possibly cultivated (Fofonoff et al. 2003).

Status: Introduced - adventive

Impact of Introduction: Potential invasive and seed contaminant

Remarks: Alopecurus geniculatus is known to hybridize with other members of the Alopecurus genus. Alopecurus x haussknechtianus is a hybrid between A. geniculatus and A. aequalis, Alopecurus x brachystylus is a hybrid between A. geniculatus and A. pratensis, Alopecurus x plettkei is s hybrid between A. geniculatus and A. bulbosus (Botanical Society of Britain and Ireland 2016). Alopecurus geniculatus , Water Meadow-foxtail, looks similar to of Alopecurus aequalis, Little Meadow-foxtail, but the flower head of A. geniculatus appears fuzzier than A. aequalis because it has longer awns (Grasses of the Columbia Basin of British Columbia 2016).

References: (click for full references)

AKEPIC (2016). Alaska Exotic Plant Information Clearinghouse database. Available: Alaska Center for Conservation Science, University of Alaska, Anchorage. [Accessed 11 May 2016]

Barnes H.F., 1930. On the biology of the gall-midges (Cecidomyidae) attacking meadow foxtail grass (Alopecurus pratensis), including the description of one new species. Annals of Applied Biology, 17(2):339-366.

Botanical Society of Britain and Ireland. 2016. Shirehampton, Bristol, BS11 9TA. Available: [Accessed 13 May 2016]

Brown, Melvin L.; J.L. Reveal, C.R. Broome, and G.F.  Frick. 1987. Comments on the vegetation of colonial Maryland, Huntia 7: 247-283.

Clayton, W.D., M.S Vorontsova K.T. Harman, and H. Williamson. 2006. GrassBase - The Online World Grass Flora. [Accessed 10 May 2016]

Cody, W.J., C.E. Kennedy, B. Bennett, and J. Staniforth. 2003. New records of vascular plants in the Yukon territory V. Canadian Field-Naturalist 117(2):278—301.

Conn, J. S., C.A. Stockdale, N.R. Werdin-Pfisterer, and J.C. Morgan. 2010. Characterizing pathways of invasive plant spread to Alaska: II. Propagules from imported hay and straw. Invasive Plant Science and Management 3(3): 276—285.

Curran, W.S., D.D. Lingenfelter, and L. Garling. 2009. Conservation Tillage Series: An introduction to weed management for conservation tillage systems. Pennsylvania State University, College of Agricultural Sciences: Agricultural Research and Cooperative Extension University Park, PA. 8 pp.

Duke, J.A., 1983. Handbook of Energy Crops. Unpublished. Purdue University, West Lafayette, Indiana, USA: Centre for New Crops and Plant Products. Available: [Accessed 11 May 2016]

Fofonoff, P.W., G.M. Ruiz, B. Steves, and J.T. Carlton. 2003. National Exotic Marine and Estuarine Species Information System. Available: [Accessed 11 May 2016]

Grasses of the Columbia Basin of British Columbia. British Columbia Ministry of Forests, Lands and Natural Resource Operations. Available: [Accessed 11 May 2016].

Integrated Taxonomic Information System (ITIS). 2012. Available: [Accessed 2012]

Hannaway, D.B., and D. Myers. 2004. Meadow foxtail (Alopecurus pratensis). Oregon, USA: Oregon State University. Available: [Accessed 11 May 2016]

Harvill Jr, A. M., T.R. Bradley, C.E Stevens, T.F. Wieboldt, D.M.E. Ware, D.W. Ogle, and G.P. Fleming. 1992. Atlas of the Virginia flora III. Virginia Botanical Associates, Burkeville, VA.

Kalusová, V., M.G. Le Duc, J.C. Gilbert, C.S. Lawson, D.J.G. Gowing, and R.H. Marrs. 2009. Determining the important environmental variables controlling plant species community composition in mesotrophic grasslands in Great Britain. Applied Vegetation Science 12: 459—471.

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR. 

Klein, H. 2011.University of Alaska Anchorage: Alaska Center for Conservation Center (UAA, ACCC). Available: [accessed 11 May 2016]

Klein, H. 2011. Water foxtail, Alopecurus geniculatus L. University of Alaska Anchorage, Alaska Natural Program. Available [Accessed 2011]

Klinkenberg, B. 2010. Alopecurus geniculatus L. In: E-Flora BC: Electronic Atlas of Plants of British Columbia. Available: [Accessed 6 February 2011]

Malyshev, L.L. 2009. Alopecurus geniculatus L. – Bent Foxtail, Marsh Foxtail. AgroAtlas. Interactive agricultural ecological atlas of Russia and neighboring countries: economic plants and their diseases, pests, and weeds. Available [Accessed 13 March 2012]

NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.0. NatureServe, Arlington, Virginia. Available [Accessed 5 August 2008, 12 May 2016]

Ohio State University (OSU). 2005. Meadow Foxtail, Alopecurus pratensis L. Ohio State Rangeland Ecology and Management Columbus, OH. 2 pp.
Online Atlas of the British and Irish flora. 2016. Available: [Accessed 12 May 2016]

Peeters, A. 2004. Wild and Sown Grasses, Profiles of a temperate species selection: ecology, biodiversity, and use. Food and Agriculture Organization of the United Nations. Blackwell Publishing. Rome, Italy. pp. 82-84.

Roberts, H. 1986. Persistence of seeds of some grass species in cultivated soil. Grass and Forage Science 41(3): 273-276.

Seguin, V., S. Lemauviel-Lavenant, D., Garon, V. Bouchart, Y. Gallard, B. Blanchet, S. Diquelou, E. Personeni, P. Gauduchon, and A. Ourry. 2010. An evaluation of the hygienic quality in single-species hay and commercial forages used in equine nutrition. Grass and Forage Science 65: 304—317.

Toogood, S.E., C.B. Joyce, and S. Waite. 2008. Response of floodplain grassland plant communities to altered water regimes. Plant Ecology 197(2):285—298.

United States Department of Agriculture, National Resource Conservation Service (USDA, NRCS). 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA. Available:

United States Department of Agriculture, Natural Resources Conservation Service (USDA, NRCS) The PLANTS Database. National Plant Data Center, Baton Rouge, LA. Available: [accessed 11 May 2016]

University of Michigan: Herbarium. 2016. Available: [Accessed 12 May 2016]

Author: Cao, L., J. Larson, L. Berent, A. Fusaro, and S. Iott

Revision Date: 5/16/2016

Citation Information:
Cao, L., J. Larson, L. Berent, A. Fusaro, and S. Iott, 2018, Alopecurus geniculatus var. geniculatus L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL,, Revision Date: 5/16/2016, Access Date: 1/19/2018

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.

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Citation information: U.S. Geological Survey. [2018]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [1/19/2018].

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