Marsilea quadrifolia L.

Common Name: European water-clover

Synonyms and Other Names:

European waterclover, European water-clover, Water shamrock, Pepperwort, Four-leaf clover

Phyzome ( Info

Identification: This herbaceous, perennial fern grows in aquatic environments from creeping, fleshing, roots containing rhizomes (Benson et al. 2004, 2008). From the roots, sprout thin green stalk bearing downy fiddleheads (furled leaflets) which will open to reveal four wedge-shaped leaflets (Benson et al. 2004, Connecticut Aquatic 2006, 2008). These 1.5 — 4 cm leaflets will float along the water’s surface or be slightly emerged (Benson et al. 2004, Campbell et al. 2010).

Marsilea quadrifolia produces thick sporocarps (spore-producing tissues) on 1—12 mm stalks near the petiole; they are oval and hairy in appearance (Benson et al. 2004, Campbell et al. 2010).

Confusion with other species:
Because its leaves are glabrous to essentially glabrous, Marsilea quadrifolia is unlikely to be confused with any other Marsilea in the flora. Likewise, the petioles of the land leaves in this species tend to be procumbent rather than stiffly erect as in the others. The branched sporocarp stalks found in M . quadrifolia are found elsewhere only in M . macropoda; the latter, however, is a hairy plant and has no distal tooth on the very large sporocarp. Marsilea minuta Linnaeus, a widespread species in the paleotropics, has recently been collected from the Florida Panhandle. It resembles M. quadrifolia in having roots both at the nodes and on the internodes and in having relatively glabrous land leaves, but it has sporocarps that are only 1.3--1.7 mm thick, with a distal tooth 0.3--0.6 mm long. Marsilea minuta also has a tendency for the terminal margins of the land leaves to be crenate rather than entire

Size: max. 20 cm

Native Range: Eurasia

Great Lakes Nonindigenous Occurrences: Found in Caucasia, western Siberia, Afghanistan, sw India, China, Japan and North America.   It was introduced to America in 1862 (CT). The introduced range of the cold temperate M. quadrifolia extends south through Pennsylvania and west to Missouri. In eastern North America, M. quadrifolia remains restricted to the more humid range of the cold temperate north. Recorded in CT, DC, IL, IN, KY, MA, ME, MO, NJ, NY, OH, PA.

First Great Lakes sighting was in 1925 in the Lake Ontario drainage.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, 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 Marsilea quadrifolia are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Michigan196120163Clinton; Great Lakes Region; Huron
New York189320145Great Lakes Region; Niagara; Oak Orchard-Twelvemile; Seneca; St. Lawrence

Table last updated 10/4/2018

† Populations may not be currently present.

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

Ecology: Marsilea quadrifolia requires moist soils and can be found in shallow, slow-moving waters environments: rivers, streams, ponds, shorelines, and ditches (Benson et al. 2004, Campbell et al. 2010). This plant prefers sandy and loamy soils. It can grow in semi-shade or no shade. From creeping rhizomes, thin green stalks rise to the water surface, each stalk bearing a single leaf with four wedge-shaped leaflets (Connecticut Aquatic 2006). When the leaves float on or just below the water surface, the leaflets have an elongated shape (Liu 1984). However in very shallow water, the stalks often are able emerge above the water’s surface and produce the characteristic four-leaf clover shape (Liu 1984).

The rhizomal structure of M. quadrifolia enables this species to reproduce vegetativley (Campbell et al. 2010). This plant also produces sporocarps (spore-producing tissues); male and female spores germinate and cross-fertilize to produce new plants (Benson et al. 2004). The sporocarps also be dispersed by waterfowl and/or remain dormant in the soil for decades (Benson et al. 2004, Campbell et al. 2010)

Means of Introduction: 1925, deliberate release, Lake Ontario drainage (U.S. EPA 2008).  Ornamental deliberate release. Many of the localities from which it is known at present are artificial bodies of water. This may indicate intentional introduction of the plant as a curiosity.

Status: It has escaped cultivation and well established in much of the Northeastern U.S. west to Iowa and Missouri for over 100 years.

Great Lakes Impacts: Current research on the environmental impact of Marsilea quadrifolia in the Great Lakes is inadequate to support proper assessment.
There exist conflicting reports on the environmental impact of this species. Marsilea quadrifolia is capable of outcompeting native aquatic and moist terrestrial species and creating monotypic vegetative stands (Benson et al 2004, Illinois Department 2013). These monospecific stands can also persist throughout the winter seasons because of the underground rhizomes (Benson et al. 2004). During the growing season M. quadrifolia plants are able to adjust the angle of the floating leaflets to optimize access to sunlight and the ability to photosynthesize (Kao and Lin 2010). This ability could allow this species to outcompete neighboring species for sunlight.  The presence of M. quadrifolia in an aquatic ecosystem can also have an effect on molluscan communities (U.S EPA 2008).

Other sources report that M. quadridfolia does not spread aggressively and poses a small ecological threat (Benson et al. 2004, Connecticut Aquatic 2006). In a survey by Henry and Myers (1983), M. quadrifolia only migrated 151 feet per year Spring Creek (Illinois); for a total range expansion of 1 mile downstream in 35 years. 

The New York Invasive Species Council ranks this species as posing an unknown ecological threat (New York Invasive 2010).

The native fern Marsilea vestita is endangered in Minnesota (Illinois Department 1996).  Whether or not M. quadrifolia has negative competitive effects or is capable of hybridizing with this endangered species is unknown. 

There is little or no evidence to support that Marsilea quadrifolia has significant socio-economic impacts in the Great Lakes.

There is little or no evidence to support that Marsilea quadrifolia has significant beneficial effects in the Great Lakes.
Marsilea quadrifolia is an edible leafy plant with high crude protein content, but has a widely varying nutrient composition depending on the season it was harvested (Dewanji et al. 1993).

European waterclover is commonly used in water gardens and aquariums (Campbell et al. 2010).

Extracts from M. quadrifolia reduced the severity of seizures in rats (Sahu et al. 2012). This species also possesses compounds that may act as acytylcholinesterase and butyrylcholinesterase inhibitors; which could play a role in the management of Alzheimer’s disease (Bhadra et al. 2012). In a study conducted by Ripe et al. (2009), extracts from M. quadrifolia were found to have antibacterial, cytotoxic and antioxidant properties. These properties may be useful in antiproliferative, antitumor, and pesticidal applications(Meyer et al. 1982 in Ripe et al. 2009).


Regulations (pertaining to the Great Lakes)
Marsilea quadrifolia is a prohibited plant species in in Illinois (GLPANS 2008).

The Great Lakes Indian and Fish & Wildlife Commission have not found M. quadrifolia within their ceded territories, but recommend that it should be controlled immediately if found (Falck and Garske 2003).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

There are no known biological control methods for this species.

There are no known physical control methods for this species.

In studies conducted in Japan, M. quadrifolia was susceptible to the herbicide bensulfuron methyl (Aida et al. 2004, Luo and Ikeda 2007).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Remarks: Marsilea minuta and M. mutica are often mistaken for M. quadrifolia, all three being glabrous, soft and fleshy when fresh. Nevertheless, the two newly documented exotic species appear better suited to the warmer climate of the Southeast, while more than a century after its initial introduction M. quadrifolia has not extended south of Maryland, Kentucky or Missouri (Henry 1983, Johnson 1993, Jacono & Johnson 2006).

References: (click for full references)

Aida, M., K. Itoh, H. Ikeda, N.  Harada, Y. Ishi, and K. Usui. 2004. Susceptibilities of some aqautic ferns to paddy herbicide bensulfuron methyl. Weed Biology and Management 4:127—135.

Benson, A. J., C.C. Jacono, P.L. Fuller, E. R. McKercher., and M. M. Richerson. 2004. Summary Report of Nonindigenous Aquatic Species in U.S. Fish and Wildlife Service Region 5. U.S. Fish and Wildlife Service, Arlington, Va. 145 pp.

Bhadra, S., P.K. Mukherjee, and A. Bandyopadhyay. 2012. Cholinesterase inhibition activity of Marsilea quadrifolia Linn. an edible leafy vegetable form West Bengal, India. Natural Product Research 26(16): 1519—1522.

Campbell, S., P. Higman, B. Slaughter, and E. Schools. 2010. A Field Guide to Invasive Plants of Aquatic and Wetland Habitats for Michigan. Michigan DNRE, Michigan State University Extension, Michigan Natural Features Inventory. 90 pp.

Connecticut Aquatic Nuisance Species Working Group. 2006. Connecticut Aquatic Nuisance Species Management Plan. State of Connecticut Department of Environmental Protection. 117 pp.

Dewanji, A., S. Matai, L. Si, S. Barik, and A. Nag. 1993. Chemical composition of two semi-aquatic  plants for food use. Plants Foods for Human Nutrition 44(1): 11—16

Falck, M. and S. Garske. 2003. Invasive Non-native Plant Management During 2002. Great Lakes Indian Fish & Wildlife Commission (GLIFWC), Odanah, WI. 68 pp.

Flora of North America.  2008.

Great Lakes Panel on Aquatic Nuisance Species (GLPANS). 2008. Prohibitied Species in the Great Lakes Region. 14 pp.

Henry, R.D. 1983. Spread of Marsilea quadrifolia in McDonough County, Illinois. Amer. Fern J. 73: 30.

Henry, R. D. and R. M. Myers. 1983. Spread of Marsilea quadrifolia in McDonough County, Illinois. American Fern Journal 73(1): 30

Illinois Department of Natural Resources. 1996. Minnesota's List of Endangered, Threatened, and Special Concern Species. 16 pp.

Illinois Department of Natural Resources. 2013. Illinois Exotic Species: waterclover Marsilea quadrifolia 8 April 2013.

Jacono, C.C and Johnson, D.M.  2006. Water-clover Ferns, Marsilea, in the Southeastern United States. Castanea 71 (1): 1–14.

Johnson, D. M. 1986. Systematics of the New World species of Marsilea (Marsileaceae). Syst. Bot. Monogr. 11: 1-87.  

Kao, W.-K. and B.-L. Lin. 2010. Phototropic leaf movements and photosynthetic performance in an amphibious fern, Marsilea quadrifolia. Journal of Plant Research 123(5): 645—653.

Liu, L. B.-L. 1984. Abscisic acid induces land form characteristics in Marsilea quadrifolia L. American Journal of Botany 71(5): pp. 638—644.

Luo, X.-Y. and H. Ikeda. 2007. Effects of four rice herbicides on the growth of an aquatic fern, Marsilea quadrifolia L. Weed Biology and Management 7:237—241.

Meyer, B.N., N.R. Ferrigni, J.E. Putnam, J.B. Jacobsen, D.E. Nicholsand and J.L. Mclaughlin, 1982. Brine shrimp; a convenient general bioassay for activeplant constituents. Planta Medica 45: 31-34.

Mickel, J. T. & A. R. Smith. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88:1-1054.  

Midwest Invasive Plant Network ( 2008. Keep a Look Out for New Aquatic Invasive Plants in the Midwest!, National Park Service. 2 pp.

New York Invasive Species Council. 2010. Final report: a regulatory system for non-native species. Department of Environmental Conservation, Albany, NY. 131 pp.

Ripe, F. A., L. Nahar, M. Haque, and M. M. Islam. 2009. Antibacterial, cytotoxic, and antioxidant activity of crude extract of Marsilea quadrifolia. European Journal of Scientific Research 33(1): 123—129

Sahu, S., G. Dutta, N. Mandal, A.R. Goswami, and T. Ghosh. 2012. Anticonvulsant effect of Marsilea quadrifolia Linn. on pentylenetetrazole induced seizure: a behavioral and EEG study in rats. Journal of Enthnopharmacology 141(1): 537—541.

U.S. EPA (Environmental Protection Agency). (2008) Predicting future introductions of nonindigenous species to the Great Lakes. National Center for Environmental Assessment, Washington, DC; EPA/600/R-08/066F. Available from the National Technical Information Service, Springfield, VA, and

Other Resources:
USGS/NAS Technical Species Profile

Plant For A Future-Species Database (1997-2000).


Author: Cao, L, and L. Berent

Contributing Agencies:

Revision Date: 4/10/2014

Citation for this information:
Cao, L, and L. Berent, 2019, Marsilea quadrifolia L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 4/10/2014, Access Date: 1/21/2019

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.