Description
Other Taxonomic Groupings - There are a number of named cultivated varieties of Lythrum salicaria(Mal et al. 1992).
Potentially Misidentified Species- Lythrum alatum (Winged Loosestrife) is native and very local along nontidal rivers in MD and VA (Brown and Brown 1984; Harvill et al. 1992). Lythrum virgatum (European Wand Loosestrife) is introduced from Europe and is very similar. It is locally escaped on the East Coast (Gleason and Cronquist 1991) and maybe in VA (Virginia Department of Conservation and Recreation 1995). Pure L. virgatum and various hybrid L. virgatum X L. salicaria cultivated varieties are planted in gardens (Mal et al. 1992).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Plantae | Magnoliophyta | Magnoliopsida | Myrtales | Lythraceae | Lythrum |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1896 | Established | Stable | Introduced | Regular Resident | Europe | Eurasia | Ornamental(Garden Escape) |
History of Spread
Lythrum salicaria (Purple Loosestrife) is native to Eurasia from central Scandinavia to the Mediterranean, the northwest Mediterranean coast of Africa, portions of central Asia, China and Japan (Thompson et al. 1997). This plant may have been imported very early as a medical herb or ornamental (Thompson et al. 1987). Early records in North America are vague as to location of occurence. The first herbarium specimen is from New Bedford MA, 1831 (Stuckey 1980). Gray (1848) gave its range as ME, MA, NY and Canada and considered it native. Lythrum salicaria reached Philadelphia by 1852. By 1900, it had spread westward to the Great Lakes, and southward to DE, DC, and NC. Isolated West Coast populations were found in WA by 1931 and CA by 1948 (Stuckey 1980; Thompson et al. 1987). Ballast from coastal and transatlantic shipping, canals, roads, and railroads, as well as escape from cultivation, were all probable means of transport. Many separate introductions are likely (Stuckey 1980; Thompson et al. 1987). As of 1985, records of L. salicaria were still strongly concentrated in the Northeast, with scattered records in the west to San Francisco CA, TX near the Gulf Coast and occurrences in TN, AL, and NC (Stuckey 1980; Thompson et al. 1987). Lythrum salicaria is abundant in the Hudson River valley, the Great Lakes basin, and the San Francisco Bay Delta (Cohen and Carlton 1995; Mills et al. 1993; Mills et al. 1997). Elsewhere in the world, Lythrum salicaria has been introduced to Australia, New Zealand, and Tasmania. (Mal et al. 1992).
In the 1930's and 1940's, Lythrum salicaria in eastern Canada and the northeastern United States had begun to develop dense populations which were causing problems in agriculture and wildlife management (Thompson et al. 1987). Six states (MN, IL, IA, OH, WA, and WI) have banned or restricted the sale or cultivation of L. salicaria and its hybrid cultivars (Strefeler et al. 1996). A biological control program, now in progress, is hoped to reduce L. salicaria to 10% of its present abundance in most of North America (Malecki et al. 1993).
In Chesapeake tidal waters,L. salicaria appears to be confined to fresh and low-salinty waters, and generally occurs as scattered populations at low densities, often in disturbed areas.
James, York, Rappahannock Rivers - Silberhorne (1995) said that he had never seen L. salicaria in his own field work (~ 30 years) in coastal VA, but that a population on the Rappahannock was being monitored by the VA Department of Game and Inland Fisheries. It has been found in Chesapeake, Williamsburg, New Kent, and Gloucester Counties (Harvill et al. 1992).
Potomac River-Lythrum salicaria was apparently planted or escaped near 'artificial fish ponds' in Washington D.C. in 1896 (Stuckey 1980). Hitchcock and Standley (1919) found it along the tidal Potomac in 'wet meadows and swamps, Hunting Creek and perhaps elsewhere'. In September 1995, Lythrum salicaria was common (scattered plants perhaps 10 m or so apart along shoreline) in Dyke marsh, Alexandria VA (Fofonoff 1995 personal observation). Mark Strong (1995) commented that he hadn't found the plant in that marsh before. Sizable patches (10-50 m across) were located on the Anacostia River near the National Arboretum and Kenilworth Aquatic Gardens (Fofonoff 1996 personal observation). It has been reported from Arlington, Fairfax, and Northumberland Counties (Harvill et al. 1992).
Patuxent River - Shreve et al. (1910) reported L. salicaria as infrequent. Anderson et al. (1968) found it rare in tidal freshwater; as did Khan (1995) in Jug Bay.
Upper Bay and Tributaries - Lythrum salicaria was found in a drainage ditch in Annapolis on a road near the South River (Fofonoff 1995 personal observation), but was not seen on the nearby shoreline, or in Rhode River wetlands. Reed (1964) found L. salicaria on ore piles beside Baltimore Harbor at Canton. One plant was found on a cobble beach at North Point State Park, Edgemere MD, just north of Baltimore Harbor (Fofonoff 1996 personal observation). Near the head of the Bay, near Havre de Grace MD, L. salicaria was abundant in a waterfront park (Fofonoff 1997-200 personal observations).
Roadside populations along I-95 were not seen in MD, but were noticed in DE near the Delaware River; and were very abundant northwards (Fofonoff 1995 personal observation).
History References - Anderson et al. 1968; Cohen and Carlton 1995; Gray 1848; Harvill et al. 1992; Hitchcock and Standley 1919; Mal et al. 1992; Malecki et al. 1993; Mills et al. 1993; Mills et al. 1997; Reed 1964; Shreve et al. 1910; Silberhorne 1995; Sipple 1995; Strefeler et al. 1996; Strong 1995; Stuckey 1980; Thompson et al. 1987
Invasion Comments
Range Status- Lythrum salicaria appears to be spreading slowly in the Chesapeake region.
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | -34.5 | |||
| Salinity (‰) | 0.0 | 19.0 | 0.0 | |
| Oxygen | ||||
| pH | 4.0000000000 | 9.0000000000 | ||
| Salinity Range | fresh-meso |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 500.0 | 500.0 |
| Typical Adult Size (mm) | 1000.0 | 1000.0 |
| Maximum Adult Size (mm) | 2700.0 | 2700.0 |
| Maximum Longevity (yrs) | 22.0 | 22.0 |
| Typical Longevity (yrs | 5.0 | 5.0 |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Lythrum salicaria (Purple loosestrife) is spottily distributed in the Chesapeake Bay area, with some locally dense populations, particulary in disturbed wetlands in Washington DC.
Aesthetic- Lythrum salicaria is requently cultivated, often in the form of hybrid cultivated varieties (with L. virgatum, European Wand Loosestrife) which are promoted as less agressive. However, L. salicaria and L. virgatum are on a list of 'Virginia Invasive Plants' which discourages cultivation of these species and their hybrid cultivars (Virginia Department of Conservation and Recreation 1996).
Habitat Change- At the present time, L. salicaria is not considered a major problem in MD or VA at this time, but populations are being monitored in MD and VA by state conservation agencies (Sipple 1995; Silberhorne 1995). Although populations of L. salicaria appear to be mostly sparse and local, at least in the lower Chesapeake basin, three species of beetles (Hylobius transversovittatus; Galerucella calmariensis; Galerucella pusilla) have been introduced to MD and VA under a joint United States Fish and Wildlife Service - United States Department of Agriculture program (Malecki et al. 1993). A dense invasion of L. salicaria occured in a restored wetland in Kenilworth Aquatic Gardens, Washington DC, prompting release of the biocontrol insects there (Swearingen 1997). Releases of biocontrol insects are continuing in Howard, Prince George, and Caroline counties in MD, and along the nontidal Susquehanna River in PA (Moser 2002). Approximately $50,000 was spent on the unsuccessful biocontrol effort in Kenilworth Aquatic Gardens in 1997, and another $50,000 for continuing biocontrol efforts in PA (Moser 2002).
References - Malecki et al. 1993; Sipple 1995; Silberhorne 1995; Swearingen 1997; Moser 2002; Virginia Department of Conservation and Recreation 1996
Economic Impacts Outside of Chesapeake Bay
Lythrum salicaria (Purple Loostrife) is regarded as a serious invader in North American wetlands, especially in the Northeast and North-central regions. Dense populations and adverse impacts have been reported from NJ to southern Canada (Thompson et al. 1987). Among economic impacts are:
Aesthetic - Lythrum salicaria is visually attractive when in bloom; cultivated as a garden plant with several commercially available varieties (including hybrids with L. virgatum), but dense wild stands are believed to decrease floral and wildlife diversity (Thompson et al. 1987). Six states (MN, IL, IA, OH, WA, and WI) have banned or restricted the sale or cultivation of L. salicaria and its hybrid cultivars (Strefeler et al. 1996).
Agriculture- Lythrum salicaria invades and degrades quality of wetland pasture. However, it is a good plant for honey production (Thompson et al. 1987).
Fisheries (=Wildlife)- Lythrum salicaria invasions of wetlands are believed to decreased food availability for furbearers and game animals (muskrat, deer, etc.) (Mal et al. 1992; Thompson et al. 1987).
Habitat Change- Lythrum salicaria is believed to adversely alter bird nesting areas (Mal et al. 1992; Thompson et al. 1987).
Thompson et al. (1987) estimate a total cost for North America of 47.9 million dollars due to decreased furbearer trapping and waterfowl hunting and reduced birding and wildlife observation. Anderson (1995) is critical of the assumptions behind this calculation. He believes adverse impacts of L. salicaria are insufficiently documented, and that more research on the plant's effects on wetland functions is needed for a rational management strategy. Estimated cost of a biological control program was $0.5 million (Thompson et al. 1987). Costs of the program, now in progress, are not yet available (Malecki et al. 1993).
References - Anderson 1995; Mal et al. 1992; Malecki et al. 1993; Strefeler et al. 1996; Thompson et al. 1987
Ecological Impacts on Chesapeake Native Species
Lythrum salicaria (Purple loosestrife) is not considered a widespread problem in MD or VA at this time (Sipple 1995; Silberhorne 1995), although dense populations are found in Delaware River marshes to the north, (Thompson et al. 1987), and locally along the Anacostia River (Fofonoff 1996 personal observation). Some populations in VA are regularly monitored (Silberhorne 1995). This plant is on lists of invasive plants in DE (Delaware Natural Heritage Program 1999), MD (Cooley 1993) and VA (Virginia Deparment of Conservation and Recreation 1999),. In Kenilwoth Aquatic Gardens,L. salicaria invaded a wetland which was in the process of restoration and was considered a threat to native plant populations. A biological control program was instituted (Swearingen 1997).
Lythrum salicaria was considered to pose a threat to breeding habitat of Canvasback ducks (Athya vallisneriae ) in the northern prairie pothole region (Alberta to Manitoba) (Thompson et al. 1987), which could affect overwintering populations in the Bay. Anderson (1995) notes that L. salicaria has not yet colonized the prairie pothole region, and considers this speculative.
Impacts noted elsewhere include:
Competition- Lythrum salicaria suppressed biomass of 41 of 43 native North American wetland plant species tested against it in paired laboratory trials (Gaudet and Keddy 1988). Its major method of competition appears to be outgrowing, overtopping, and shading native plants (Edwards et al. 1995). Replacement of native flora has been widely observed in inland and coastal wetlands (Thompson et al. 1987). However, at least some native species frequently remain, and declines in biomass of native species are frequently not well documented. Some native species, including Phalaris arundinacea (Reed Canary-Grass), Polygonum spp. (Knotweeds, Tearthumbs), and Typha spp. (Cattails), do seem to compete successfully in trials (Gaudet and Keddy 1988; Anderson 1995) . Gaudet and Keddy's experiments were carried out under optimal nutrient and water level conditions. Lythrum salicaria may be less competitive in low-nutrient wetlands, and under conditions of fluctuating water levels (Edwards et al. 1995). It is highly productive, and could increase total biomass of a wetland community; so increases in its biomass may not necessarily imply decreases in native species (Anderson 1995).
Habitat Change - Invasions of L. salicaria can alter preferred nesting areas for birds and habitat for other marsh animals such as turtles (Thompson et al. 1987). Dense growths may restrict access to water and provide cover for predators (Mal et al. 1992). However, a variety of birds including Agelaius phoniceus (red-winged blackbirds), Cistothorus palustris ( marsh wrens), and Nycticorax nycticorax (night herons) do nest in L. salicaria stands (Anderson 1995).
Food/Prey- Lythrum salicaria is probably an inferior food for insects, waterfowl, and mammals (Thompson et al. 1987). But waterfowl and fish eat the seeds, and deer and muskrat graze the plants, as do a variety of native insects (Anderson 1995). Anderson found that 7% of a coastal MA population had signs of stem herbivory in spring, suggesting to us that L. salicaria is not a strongly preferred food. In British Columbia, there is concern that L. salicaria's invasion in the Fraser River estuary may affect native wetlands and juvenile salmon habitat, by affecting detritus foodwebs. Lythrum salicaria decomposes more rapidly than the present dominant (Carex lyngbyei, Lynbye's Sedge), which might result in a depletion of food resources for the detritovores on which juvenile salmon feed (Grout et al. 1997). The extent to which L. salicaria invasions might affect detritus pathways in Chesapeake wetlands is unknown.
Hybridization- Lythrum salicaria has hybridized extensively with the native L. alatum(Winged Loosestrife) in MN. Crosses are fertile and extensive introgression appears to have taken place there. Introgression of L. alatum genes may be involved in the evolution of 'weedy' L. salicaria in North America (Strefeler et al. 1996). Lythrum alatum is restricted to the Piedmont and Mountain regions in our area (Brown and Brown 1984; Harvill et al. 1992).
Anderson (1995) argues that widely accepted perception of negative impacts of L. salicaria on native communities may be true, but needs further documentation.
It should be noted that control methods, including burning, flooding, cutting, and herbicides are all likely to have adverse effects on the native wildlife (Anderson 1995; Thompson et al. 1987). Biological control also carries risks for native species, though extensive testing has been done to minimize those risks (Malecki et al. 1993).
References - Anderson 1995; Brown and Brown 1984; Delaware Natural Heritage Program 1999; Edwards et al. 1995; Gaudet and Keddy 1988; Grout et al. 1997; Harvill et al. 1992; Mal et al. 1992; Malecki et al. 1993; Strefeler et al. 1996; Thompson et al. 1987; Sipple 1995; Silberhorne 1995; Virginia Division of Conservation and Recreation 1999
Ecological Impacts on Other Chesapeake Non-Native Species
Dense populations of Lythrum salicaria (Purple Loosestrife) are quite localized in the Chesapeake Bay watershed, so that interactions with other exotic biota may be limited.
Hybridization- Lythrum salicaria may hybridize with cultivated varieties of L. virgatum (European Wand Loosestrife), a Eurasian species which is sometimes planted, but has not been collected in the wild in the Chesapeake Bay watershed. Cultivated L. virgatum and L. salicaria in MN populations could not be distinguished by isozyme analysis, indicating that extensive introgression between these species may have already taken place Genetic exchange with an other exotic could affect the competitiveness of introduced L. salicaria populations (Strefeler et al. 1996).
Food/Prey - Three species of European beetles (Hylobius transversovittatus; Galerucella calmariensis; Galerucella pusilla) were released in MD and VA in 1992 by the United States Department of Agriculture- Animal and Plant Health Inspection Services for biological control of L. salicaria. The beetles were also released in NY, PA, MN, OR, WA, and Canada. These insects have a high degree of specificity, and are effectively dependent on L. salicaria for their survival (Malecki et al. 1993).
References - Malecki et al. 1993; Strefeler et al. 1996
References
Anderson, Mark G. (1995) Interactions between Lythrum salicaria and native organisms: A critical review, Environmental Management 19: 225-231Anderson, Richard D.; Brown, Russell, G.; Rappleye, Robert D. (1968) Water quality and plant distribution along the upper Patuxent River, Maryland, Chesapeake Science 9: 145-156
Blossey, Bernd; Notzold, Rolf (1995) Evolution of increased competitive ability in invasive nonindigenous plants., Journal of Ecology 83: 887-889
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Harvill, A. M.; Bradley, Ted R.; Stevens, Charles E.; Wieboldt, Thomas F.; Ware, Donna M. E.; Ogle, Douglas W.; Ramsey, Gwynn W.; Fleming, Gary P. (1992) Atlas of the Virginia Flora, , Burkeville, VA. Pp.
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1995 Introduced plants in the Chesapeake Bay region, conversation with Paul Fofonoff.
1995 ---missing info----. Conversation
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September 24 1997 email, Loosestrife biocontrol beetles. jil_swearingen@nps.gov National Park Service, Washington DC
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1999 Invasive Alien Plant Species of Virginia. http://www.state.va.us/~dcr/dnh/invlist.htm