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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.

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Common name: water-cress

Synonyms and Other Names: Rorippa nasturtium-aquaticum (L.) Hayek, Nasturtium nasturtium-aquaticum, (L.) H. Karst., Sisymbrium nasturtium-aquaticum L., Nasturtium officinale var. siifolium (Rchb.) W.D.J. Koch, watercress, water cress, yellowcress

Taxonomy: available through www.itis.gov

Identification: Watercress is a fast-growing, aquatic or semi-aquatic, perennial herb that appears floating or prostrate in mud. Stems are succulent, hollow, and branched, rooting at nodes. Leaves are pinnately divided; leaflets 3–7, oval to egg-shaped, entire to wavy-edged. Flowers are small (6 mm, diameter) and white, in terminal clusters. Sepals are erect, green, about 3 mm long; petals are white, about 4 mm long with 4 long stamens attached near their bases to the filaments. Ovary about 3 mm long, style short, stigma with two lobes. Fruits borne on spreading pedicels and slightly curved upward. The double row of seeds in each half of the siliqua is a well marked character. The valves of the ripe siliqua are beaded; seeds suborbicular and compressed, with 25 alveoli on each side of the testa.  This species can grow to a height of 50-200 cm, with a stem up to 20 mm in diameter and with leaves up to 27 cm in length.

Size: 4–25 in. long

Native Range: Eurasia & Asia.

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

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

Ecology: Nasturium officinale is a perennial herb that grows at the water’s surface along the edges of cold lakes and reservoirs, and along slow-moving streams and rivers (Benson et al. 2004, Howard and Lyon 1952, Robert W. Frackman Herbarium 2012). The depth of water in commercial watercress beds is about 3-6 in (Howard and Lyon 1952). This species is well-suited to water that is slightly alkaline and it is usually absent from stagnant water. Watercress prefers to take roots in limey, gravelly sediment (Robert W. Freckman Herbarium 2012). Watercress appears to be intolerant of heavy shade (Howard and Lyon 1952). A relatively high humidity is required for optimum growth (Howard and Lyon 1952).

Nasturium officinale overwinters with terminal buds up to 10 cm in length (Howard and Lyon 1952). Watercress is most abundant in summer and autumn and flowers between March to October. This species is self-compatible and produces ~ 15 fruits per inflorescences and 26 seeds per fruit (Howard and Lyon 1952). This species is also capable of vegetative reproduction (Howard and Lyon 1952).

Means of Introduction: Intentionally introduced by green industry and cultivation. Fragments are dispersed unintentionally by wind, water, and animals.

Status: Established. Naturalized throughout North America, north to Alaska.

Impact of Introduction: Watercress may be a noxious weed or invasive. In arid regions of western states, it can alter function and block streams. It was reported to block water flow in springs in South Central Wisconsin. Extracts can attract schistosomiasis host Biomphalaria glabrata (snail).

Watercress is an edible green with a peppery flavor that is commonly used in salads, as a garnish, or cooked, and which contains significant amounts of iron, calcium and folic acid, in addition to vitamins A and C. Many benefits from eating watercress are claimed, such as that it acts as a mild stimulant, a source of phytochemicals and antioxidants, a diuretic, an expectorant, and a digestive aid. It may also have cancer-suppressing properties, and is widely believed to help defend against lung cancer. 

References: (click for full references)

Bahramikia, S. and R. Yazdanparast. 2010. Antioxidant efficacy of Nasturtium officinale extracts using various in vitro assay systems. Journal of Acupuncture and Meridian Studies 3(4): 283—290.

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.

Bleeker, W., M. Huthmann, and H. Hurka. 1999. Evolution of Hybrid Taxa in Nasturtium R.Br. (Brassicaceae). Folia Geobotanica 34(4): 421—433.

Centers for Disease Control and Prevention (CDC). 2013. Fascioliasis (Fasciola Infection). Available http://www.cdc.gov/parasites/fasciola/. Accessed 29 April 2013.

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

Duman, F. and F. Ozturk. 2010. Nickel accumulation and its effect on biomass, protein content and antioxifative enzymes in roots and leaves of watercress (Nasturtium officinale R. Br.). Journal of Environmental Sciences (China) 22(4): 526—532.

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

Gill, C. I., S. Haldar, L.A. Boyd, R. Bennett, J. Whiteford, M. Butler, J.R. Pearson, I. Bradbury, and I. R. Rowland. 2007. Watercress supplementation in diet reducs lymphocyte DNA damage and alters blood antioxidant status in healthy adults. THe american Journal of Clinical Nutrition 85(2): 504—510.

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

Howard, H.W., Lyon, A.G. 1952. Nasturtium Officinale R. Br. (Rorippa Nasturtium-Aquaticum (L.) Hayek). The Journal of Ecology 40 (1): 228-245. 

Howard-Williams, C., J. Davis, and S. Pickmere. 1982. The dynamics of growth, the effects of changing area and nitrate uptake by watercress Nasturtium officinale R. Br. in a New Zealand stream. Journal of Applied Ecology 19(2): 589—601.

Keser, G. and S. Saygideger. 2010. Effects of lead on the activities of antioxidant enzymes in watercress, Nasturtium officinale R. Br. Biological Trace Element Research 137(2): 235—243.

Kullberg, R. G. 1974. Distribution of aquatic macrophyte related to paper milll effluents in a southern Michigan stream. American Midland Naturalist 91(2): 271—281.

Newman, R. M., Z. Hanscom, and W. C. Kerfoot. 1992. The watercress glucosinolate-myrosinase system: a feeding deterrent to caddisflies, snails and amphipods. Oecologia 92(1): 1—7.

Ozturk, F., F. Duman, Z. Leblebici, and R. Temizgul. 2010. Arsenic accumulation and biological responses of watercress (Nasturtium officinale  R. Br.) exposed to arsenite. Environmental and Experimental Botany 69(2): 167—174.

Redding, T.S., Midlen, A. 1997. The treatment of aquaculture wastewaters - A botanical approach. Journal of Environmental Management 50 (3): 283-299.

Reznicek, A.A., E. G. Voss, and B. S. Walters. 2011. Michigan Flora Online. University of Michigan. Available http://michiganflora.net/species.aspx?id=670. Accessed 12 April 2013.

Robert W. Freckman Herbarium. 2012. Family Brassicaceae. Nasturtium officinale R.Br. Available http://wisplants.uwsp.edu/scripts/detail.asp?SpCode=NASOFF. Accessed 29 April 2013.

State of Washington, Department of Ecology.  2013. Nasturtium officinale R. Br. Formerly called Rorippa nasturtium-aquaticum (L.) hayek, water cress. Available http://www.ecy.wa.gov/Programs/wq/plants/plantid2/descriptions/rornas.html. Accessed 29 April 2013.

Tardio, M Pardo-De-Santayana, Morales, R. 2006. Ethnobotanical review of wild edible plants in Spain. Botanical Journal of the Linnean Society 152 (1): 27-71.

Tenorio, R.C., Drezner, T.D. 2006. Native and invasive vegetation of karst springs in Wisconsin's Driftless area. Hydrobiologia 568: 499-505.

Walsh, J. A. and K. Phelps. 1991. Development and evaluation of a technique for screening watercress (Rorippa nasturtium-aquaticum) for resistance to watercress yellow spot virus and crook-root fungus (Spongospora subterranea f. sp. nasturtii). Plant Pathology 40(2): 212—220.

Wisconsin Department of Natural Resources (WI DNR).  2010. Watercress: Nasturtium officinale.  5 pp. Available http://dnr.wi.gov/topic/Invasives/documents/classification/Nasturtium%20officinale.pdf. Accessed 29 April 2013.

Other Resources:
GLIFWC Maps

The PLANTS Database 2008. National Plant Data Center, NRCS, USDA. Baton Rouge, LA 70874-4490 USA. http://plants.usda.gov/

Connecticut Botanical Society

Wikipedia

Calflora

Turner Photographics

US Fish and Wildlife Service Ecological Risk Screening Summary for Nasturtium officinale

Author: Cao, L, and L. Berent

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.