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

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).

This species was introduced to America in 1862 in Connecticut. 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. 

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)

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Beneficial

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

Potential:
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.

No significant socioeconomic impacts have been reported for this species in the Great Lakes.

There is little or no evidence to support that Marsilea quadrifolia has significant beneficial effects in the Great Lakes.

Realized:
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). Edible uses: young stems and leaves are rich in starch. Medicinal uses: antidote, febrifuge.

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

Potential:
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.

Control
Biological
There are no known biological control methods for this species.

Physical
There are no known physical control methods for this species.

Chemical
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.

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.

Many ferns also contain thiaminase, an enzyme that robs the body of its vitamin B complex. In small quantities this enzyme will do no harm to people eating an adequate diet that is rich in vitamin B, though large quantities can cause severe health problems. The enzyme is destroyed by heat or thorough drying, thus cooking the plant will remove the thiaminase (Plants For A Future, 2014).