The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Alopecurus geniculatus
Alopecurus geniculatus
(water foxtail)

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Alopecurus 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).

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Alopecurus geniculatus are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AK194020076Anchorage; Chichagof Island; Kuiu-Kupreanof-Mitkof Islands; Lower Kenai Peninsula; Lynn Canal; Upper Kenai Peninsula
AZ194119411Lower Colorado Region
CA190019001California Region
CT190019001New England Region
DC190019001Middle Potomac-Anacostia-Occoquan
ID191219121Pacific Northwest Region
IL1860199514Bear-Wyaconda; Cahokia-Joachim; Chicago; Des Plaines; La Moine; Little Wabash; Lower Fox; Lower Illinois; Lower Illinois-Lake Chautauqua; Lower Illinois-Senachwine Lake; Lower Sangamon; Middle Kaskaskia; Spoon; Upper Fox
IN191819181Ohio Region
ME189318931New England Region
MD190019001Mid Atlantic Region
MA187418741New England Region
MI190019944Clinton; Great Lakes Region; Saginaw; Thunder Bay
MN190020084Chippewa; Des Moines Headwaters; Lower Big Sioux; Minnesota
MT188420112Cottonwood; Fort Peck Reservoir
NE190019001Missouri Region
NH190019002Piscataqua-Salmon Falls; Winnipesaukee River
NJ191519151Mid-Atlantic Region
NY185820083Middle Hudson; Seneca; St. Lawrence
OH188220089Hocking; Lake Erie; Licking; Lower Scioto; Mohican; Sandusky; Scioto; Southern Lake Erie; Upper Scioto
OK189618961Arkansas-White-Red Region
OR1884200938Alsea; Alvord Lake; Beaver-South Fork; Coast Fork Willamette; Coquille; Donner und Blitzen; Goose Lake; Guano; Jordan; Lake Abert; Lost; Lower Columbia; Lower Columbia-Sandy; Lower Crooked; Lower Willamette; Middle Columbia-Hood; Middle Rogue; Middle Willamette; Necanicum; Pacific Northwest Region; Siletz-Yaquina; Siltcoos; Silvies; Siuslaw; Sixes; South Umpqua; Sprague; Summer Lake; Tualatin; Umpqua; Upper Crooked; Upper Deschutes; Upper Klamath; Upper Klamath Lake; Upper Rogue; Upper Willamette; Wallowa; Wilson-Trusk-Nestuccu
PA190019001Lower Delaware
RI194119411New England Region
SD190019002Grand-Moreau; Lake Oahe
TN199919991Lower French Broad
UT189420111East Fork Sevier
WA190220112Pacific Northwest Region; Strait of Georgia
WI190019916Des Plaines; Duck-Pensaukee; Lower Fox; Northwestern Lake Michigan; Peshtigo; Southwestern Lake Michigan

Table last updated 4/21/2024

† Populations may not be currently present.

* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

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: Naturalized throughout the Great Lakes region.

Impact of Introduction: A potential seed contaminant that can be introduced to new locations.

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: http://aknhp.uaa.alaska.edu/maps-js/integrated-map/akepic.php. 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: bsbi.org/maps?taxonid=2cd4p9h.fy. [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. 
http://www.kew.org/data/grasses-db.html [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: http://www.hort.purdue.edu/newcrop/Indices/index_ab.html. [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: http://invasions.si.edu/nemesis/. [Accessed 11 May 2016]

Grasses of the Columbia Basin of British Columbia. British Columbia Ministry of Forests, Lands and Natural Resource Operations. Available: https://www.for.gov.bc.ca/hfd/pubs/Docs/Wp/Wp45/Wp45-e.pdf. [Accessed 11 May 2016].

Integrated Taxonomic Information System (ITIS). 2012. Available: http://www.itis.gov/index.htm. [Accessed 2012]

Hannaway, D.B., and D. Myers. 2004. Meadow foxtail (Alopecurus pratensis). Oregon, USA: Oregon State University. Available:http://forages.oregonstate.edu/php/fact_sheet_print_grass.php?SpecID=4&use=Forage. [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:http://aknhp.uaa.alaska.edu/wp-content/uploads/2013/01/Alopecurus_geniculatus_BIO_ALGE2.pdf. [accessed 11 May 2016]

Klein, H. 2011. Water foxtail, Alopecurus geniculatus L. University of Alaska Anchorage, Alaska Natural Program. Available http://aknhp.uaa.alaska.edu/botany/akepic/non-native-plants-alaska/. [Accessed 2011]

Klinkenberg, B. 2010. Alopecurus geniculatus L. In: E-Flora BC: Electronic Atlas of Plants of British Columbia. Available: http://www.geog.ubc.ca/biodiversity/eflora/index.shtml. [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. Availablehttp://www.agroatlas.ru/en/content/related/Alopecurus_geniculatus/. [Accessed 13 March 2012]

NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.0. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. [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.
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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: http://plants.usda.gov/java/.

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

University of Michigan: Herbarium. 2016. Available: http://michiganflora.net/species.aspx?id=2002. [Accessed 12 May 2016]

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

Revision Date: 3/9/2022

Citation Information:
Cao, L., J. Larson, L. Berent, A. Fusaro, and S. Iott, 2024, Alopecurus geniculatus L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2681, Revision Date: 3/9/2022, Access Date: 4/22/2024

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. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [4/22/2024].

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