 |
|
|
||||
| NAS - Nonindigenous Aquatic Species |
Translate this page with 
Common Name: European water-clover
Synonyms and Other Names: Water shamrock; Pepperwort; Four-leaf clover
Taxonomy: available through 
Identification:
Plants forming diffuse clones. Roots arising at nodes and 1--3 on internodes. Petioles 5.4--16.5 cm, sparsely pubescent to glabrous. Pinnae 7--21 × 6--19 mm, sparsely pubescent to glabrous. Sporocarp stalks ascending, frequently branched, attached 1--12 mm above base of petiole; unbranched stalks or ultimate branches of stalks 3--16 mm; common trunk of branched stalks 1--4 mm (rarely 2--3 unbranched stalks attached separately to same petiole). Sporocarps perpendicular to ascending, 4--5.6 × 3--4 mm, 2.3--2.8 mm thick, rounded, oval, or elliptic in lateral view, pubescent but soon glabrate; raphe 1.4--1.9 mm, proximal tooth usually absent, distal tooth absent or 0.1--0.2 mm. Sori 10--17.
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
|
||||
| NAS - Nonindigenous Aquatic Species |
Translate this page with
Common Name: European water-clover
Synonyms and Other Names: Water shamrock; Pepperwort; Four-leaf clover
Taxonomy: available through
Identification:
Plants forming diffuse clones. Roots arising at nodes and 1--3 on internodes. Petioles 5.4--16.5 cm, sparsely pubescent to glabrous. Pinnae 7--21 × 6--19 mm, sparsely pubescent to glabrous. Sporocarp stalks ascending, frequently branched, attached 1--12 mm above base of petiole; unbranched stalks or ultimate branches of stalks 3--16 mm; common trunk of branched stalks 1--4 mm (rarely 2--3 unbranched stalks attached separately to same petiole). Sporocarps perpendicular to ascending, 4--5.6 × 3--4 mm, 2.3--2.8 mm thick, rounded, oval, or elliptic in lateral view, pubescent but soon glabrate; raphe 1.4--1.9 mm, proximal tooth usually absent, distal tooth absent or 0.1--0.2 mm. Sori 10--17.
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
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.
Ecology: M. quadrifolia is an aquatic fern that grows from creeping rhizomes anchored in the muddy bottoms of shallow ponds and lakes. This plant prefers light (sandy) and medium (loamy), acid or neutral or basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It requires moist or wet soil and can grow in water. From creeping rhizomes, thin green stalks rise to the water surface, each stalk bearing a single shamrock-like leaf with four wedge-shaped leaflets. Leaves usually float on or just below the water surface, however in very shallow water (2-3” deep) the stalks often are able emerge 3-4” above the surface.
Means of Introduction: 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.
Impact of Introduction: M. quadrifolia may crowd out native wetland plants by forming dense stands. “Although we have found no reports of toxicity for this species, a number of ferns contain carcinogens so some caution is advisable. 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, so cooking the plant will remove the thiaminase” (Source: Plant For A Future).
Edible uses: young stems and leaves; rich in starch. Medicinal uses: antidote, febrifuge.
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
Flora of North America. 2008. www.eFloras.org
Johnson, D. M. 1986. Systematics of the New World species of Marsilea (Marsileaceae). Syst. Bot. Monogr. 11: 1-87.
Mickel, J. T. & A. R. Smith. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88:1-1054.
Jacono, C.C and Johnson, D.M. 2006. Water-clover Ferns, Marsilea, in the Southeastern United States. Castanea 71 (1): 1–14.
Henry, R.D. 1983. Spread of Marsilea quadrifolia in McDonough County, Illinois. Amer. Fern J. 73: 30.
Other Resources:
Plant For A Future-Species Database (1997-2000). http://www.pfaf.org/index.php
USDA/NRCS PLANTS Database
Author: Ling Cao
Contributing Agencies: 
NOAA - GLERL
Revision Date: 7/20/2008 Citation for this information:
Ling Cao. 2009. Marsilea quadrifolia. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/factsheet.asp?SpeciesID=293> Revision Date: 7/20/2008
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|