4.15.2000

Purple Loosestrife Outline and Bibliography

Prepared by Amy Wiebe, April 2000

Purple Loosestrife (Lythrum salicaria)

In January 2000, the U.S. Fish and Wildlife Service declared purple loosestrife "Public Enemy #1 on Federal Lands".

Purple loosestrife also ranked # 2 on The Nature Conservancy weed survey of most troublesome weeds in wildlands for 1996.

A. Taxonomy

Family: Lythraceae- Loosestrife Family

• Lythraceae is composed of approximately of 22 genera encompassing 500 species worldwide

• Representatives of this family include herbs, shrubs, and trees; several of which are cultivated as ornamentals

Genus: Lythrum

• 12 species of Lythrum in the continental United States

• 3 of these 12 species L. hyssopifolia, L. virgatum, and L. salicaria were non-native

Species: salicaria

Common Names: over ten common names recorded, most common "purple loosestrife"

B. Geographical Distribution

1. Origin of Distribution

• European and Asian origin

• Range extends across Europe to Russia.

• Found in most coastal areas of Europe

• There is a gap in the range in western Mongolia, China, and Tibet

• Japan was the center of the Asian range  

• Purple loosestrife has also invaded other temperate and subtropical areas and is now known in eastern Africa, Australia, and Tasmania

2. Arrival and Establishment in North America

• First recorded in the early 1800' s

• Introduced via seed in a ship ballast

• Introduced into New England or Upper New York State

• Also arrived on imported wool or sheep brought over from Europe

• Immigrants may have brought loosestrife seed with them

• Horticulturists carried loosestrife seed

• The repeated introduction of purple loosestrife from different sources contributed to the genetic diversity of the North Amer ican population.

3. Increasing Range of Purple loosestrife (1830-1880)

• Most of the new records of loosestrife establishment occurred along commerce routes or at ports.

• Most dispersal was though interconnected waterways of marine and interior wetlands

• Drastically altered landscape created opportunity for invasion

• Dredging, excavating channels, and adding canals altered waterways

• Access to the interior of the continent and wetland disturbance increased

4. From 1880 to 1900

• Marine commerce was the principal mode of spread

• Early frontier families purposely carried seed because of its bright purple flowers and herbal properties

• Seeds were also hitchhikers in mud attached to wagon wheels of the pioneers as they traveled across the national highway

• Acclaimed for the attractiveness of its flowers to honey bees

5. From 1900-1985

• The national superhighway and the construction of dams and storage facilities for western irrigation create new habitat for loosestrife

• The recent infestations in California, Idaho, Washington, and Wyoming are all in irrigation areas

6. Today

• Since 1940, purple loosestrife has spread at an annual mean rate of 645 km²

• >50% of plant biomass has been displaced in some wetlands

• Continues to colonize new areas through waterways

• Horticulture escapes and intentional plantings

• The inclusion of purple loosestrife in gardens and borders has continued throughout Canada and the United States.

• Several large nurseries have developed their own horticultural stocks that continue to be important sources of dispersal

• Wade (1985) examined mixes of "wildflowers" and native prairie herbs and grasses found 25% of the native-plant seed mixes contained alien species; 10% of the lists with alien seeds included L. salicaria.

C. Biology

General

• Perennial

• Polyploid (4x, 6x)

• Reproduce by seeds and some vegetative regrowth from rootstock and cut stems

• At maturity plants range in height from 1.5 to 8 feet

• May have between 30-50 stalks

• Established loosestrife plants may live over 22 years

• Can cross with Lythrum alatum in natural settings

1. Rootstock

• Massive rootstock

• Woody

• Stores nutrients for next year's growth

• Likes it's feet wet

2. Stems

• Erect stems

• Increasing amount of stems each year

• In pure stands, stalks can reach 80,000 per acre

• Seedlings and young growth remain smooth

• The angular stems, which may be four to six sided, are usually pubescent

• Evenly spaced nodes

• Loosestrife stems become woody with age

• The remains of last year's crop can still be seen the next summer

• Develop aerenchyma when stems and roots are underwater

3. Leaves

• Broad-leafed

• Lower leaves opposite leaf arrangement , or in whorls of three or four

• Upper leaves alternate

• Loosestrife leaves are long and narrow and closely attached to the stem

• Without petioles

• Prominent leaf venation with pinnate veins

• Mid vein ends in a common vein running parallel to and extending the entire leaf margin

4. Flowers

• Blooms from mid-June to late September

• Purple flowers are generally six petaled although there is variation

• The erect stalk is composed of numerous flowers closely attached to the leaf axils of flower-bearing branches

• Flowers begin to open at the base of the spike and progress upward

• Flowers lack fragrance

• Produces large amounts of nectar

• Flower duration varies. Taller plants are the first to flower and have the longest flowering duration

• Herkogamous--spacial seperation of stamens and anthers

• Three lengths of styles occur with three combinations of anther lengths on different plants

• Three forms of flowers coexist in wild populations in nearly equal frequencies

• Mid style morph more successful as female flower

• Plants outcross with flowers of matching stigma and style lengths for best results

• Reduced seed number if non-matched mating occurs

• Increased tendency for plants to self-pollinat

• Pollenated by insects: honey bees, leaf cutter bees, carpenter bees, bumble bees, European white butterflies, common sulphur, and wood nymph.

• Any insect with a proboscis > 6 mm.

• Assortative pollination occurs among morphs

5. Pollen

• The size and color of the pollen grains depend on the whether they come from long, mid, or short stamen morph.

• The long style morph (30-38 µm x 20-26 µm) has green pollen

• the mid style morph (23-26 µm x 13-16 µm) has yellow pollen grains

• short style morph (20-25 µm x 11-13 µm) produces yellow pollen grains

• Yellow pollen grains are more lipid rich, while larger green are more starchy

• Lack gerninal pores

6. Seed

• The fruit is an oblong capsule with two valves that hold many small seeds.

• The seed output is dependent on its age, size, and vigor.

• Mature plants produced a mean of 90 seeds per capsule, 1, 000 capsules per stem, 30 stems per plant

• The total number of seeds produced per plant is estimated at 2,700,000

• The flat, thin-walled seeds

• Tan in color

• No endosperm

• 2 cotyledons

• 400 x 200 microns in size

• 5 x 10-5 average seed weight

• Dormancy enforced by burial--no emergence after 2cm.

D. Dispersal and Spread

• Quickly colonizes new areas

• Once established it can threaten all wetlands, lakes, rivers, and streams in a watershed

1. By Seed

• Primarily by water
• Most loosestrife seeds sink, but rise to the surface following germination
• Water currents transport seedlings to new areas

• The small lightweight seeds can also be dispersed by wind
• Wind dispersal is limited to within the first 10 m from the parent plant

• Seeds are transported in the mud stuck to waterfowl or small mammals

• Humans move seed as they move from one wetland to another
• Horticulture escapes

2. By Stems

• Cut stems with one or two nodes present produced shoots and adventitious roots
• Broken stems can float downstream or root near the base of the plant

3. No rhizomes

E. Seedling Establishment

• Most seedling establishment occurs in late spring and early summer

• Germinate from seeds that have survived at least one winter

• 92% successful germination of loosestrife seedlings in a 30 day period

• The only requirements for germination is temperature and light

• Seedling density approach 10,000-20,000 plants/m²

• When seedlings are covered by at least 10 inches of water they become dormant and the developed leaves fall off. The tips of the stems are able to produce new leaves and adventitious roots.

1. Temperature

• Critical temperature for emergence between 15-20º C

• Germination is depressed at temperatures below 20º C

• No germination occurs below 14º C

2. Soils

• Optimum conditions are moist soils

• Neutral to slightly acid pH

• Found in a wide range of soil textures and types: rock crevasses, gravel, sand, clay, and organic soils

3. Light

• Growth maximized under full sunlight

• Can survive in as low as 50% full sun

• Loosestrife responds to reduced illumination by increasing leaf size and decreasing leaf thickness

4. Nutrients

• Reductions in P, N, and K increase the root to shoot ratio

• Most sensitive to N

F. Stability of Purple Loosestrife Stands

• When first invading it remains rare or in a local setting

• In 20-40 years becomes a serious weed problem

• Self-replacing stands

Factors that account for the stability of North American stands

• Insect fauna missing key herbivores that reduce the vigor of European plants

• More adaptive and vigorous forms of purple loosestrife may have appeared in the North American populations

G. Habitat

• Northern distribution reaches the 65th parallel and its southern distribution is along the Mediterranean in North Africa

• Altitude below 600 m

• Areas where the soil is damp and saturated

• Floodplains

• Found in marshes, on riverbanks, or along roadside ditches

• Prefer disturbance

H. Purple loosestrife look alikes

• Blazing star (Liatris spicata)

• Blue Vervain (Verbena hastata)

• Fireweed (Epilobium angustifolium)

• Swamp loosestrife (Decodon verticillatus)

• Winged loosestrife (Lythrum alatum)

I. Horticulture varieties

• Atropurpureum
• Roseum Superbum
• Brightness
• Lady Sackville
• Robert and the Beacon
• Dropmore purple
• Rose Queen
• The Rocket
• Perry's Variety
• Happy Firecandle
• Columbia Pink

J. Why is it a problem?

Ecological

1. Out-competes native vegetation

2. Forms a monoculture

3. Biodiversity is reduced

4. Superior competitive ability

• Competitive ranking of L. salicaria and five other common wetland species. Lythrum >Cyperus > Juncus >Eleocharis > Mimulus > Verbena.

• Lythrum salicaria dominates Typha sp.(cattail) under direct competition and will displace Typha sp. over the course of four years

• Following the establishment of L. salicaria the growth of 44 native wetland species declined

• 20 wetland species representing a range of life histories in a variety of habitat conditions was examined over 5 years, Lythrum salicaria dominanted all but one treatment

5. Detrimental effects on habitat quality for wildlife

• Not meet the needs of most waterfowl species for nesting or shelter

• The dense growth limits the access to open water

• Offers shelter to foxes and raccoons that may feed on unsuspecting eggs and nestlings

• Exclude desirable waterfowl food plants

6. Bird density in purple loosestrife stands was higher, bird diversity was much lower.

7. The reduction in habitat diversity and alterations in trophic interactions can threaten already endangered species.

• Bulrush (Scirpus longii) in Massachusetts

• Dwarf spike rush (Eleocharis parvula) in New York

• Bog turtle (Clemmys muhlenbergi) in the eastern United States

• Black tern (Chlidonias niger) in the northern prairies and Great Plains

• Canvasback (Aythya valisineria)

Economical

1. Agriculture

• Less palpable to livestock than native forbes and grasses

• Monetary losses due to decrease in wetland pastures and hay meadows for grazing

• Infestation of wild rice stands in California and Wisconsin

2. Water Flow

• Water flow and irrigation systems can be impeded by purple loosestrife

• Impenetrable to boats

• Increased cost of drainage ditch rehabilitation and maintenance

3. Hinder recreational activities

• Habitat alterations may have impacts on fish and spawning grounds, thus decreasing fish populations

• Reduction in bird population for hunting

• Recreational activities like fishing and hunting are physically obstructed

4. Wetland restoration projects could be jeopardized due to the invasion of purple loosestrife

K. Benefits

1. Honey production

• Long flowering season

• Large quantities of nectar

• Flowers spread easily naturally

• Honey is rather dark and considered inferior

2. Attractive in Gardens

• Bright purple flowers

• No rhisomes so will not spread in garden

• Persistant display of color

3. Medical treatment

• Diarrhea, dysentery, bleeding, sores, ulcers

• Current research is investigating the benefits of loosestrife tea treatment for diabetes

4. Purple loosestrife smoke believed to drive away serpents and flies

L. Control

Mechanical Control

1. Hand pulling

• Most accurate control method

• Labor intensive

• Physical removal of all the stems, the branches, and the perennial rootstock

• Young plants (1-2 years old) with smaller rootstocks are easiest to remove

• Soil disturbance from hand removal needs to be minimized, to prevent seedling reestablishment

• Not very practical for large stands of purple loosestrife, but efficient for small stands or isolated plants

2. Clipping or cutting of loosestrife stems

• Cutting of young plants before rootstock expansion is most effective in reducing the same year's biomass

• Significant reduction in the same year's growth

• Roots and seeds re-establish the next year or even later in the same year

• Needs to be repeated year after year

• Pre-flower clipped plants produce a greater amount of seed

• Cut stems may result in vegetative regeneration and clonal spread

• Native vegetation in the area may be disturbed by treatment creating opportunity for new loosestrife seedlings to become established

Cultural Control

1. Large-scale water manipulation

• Mixed results

• The age of the plant, the frequency of flooding, and the duration of inundation can alter the success

• Duration of the high water depth during loosestrife's most active growing period has been shown to result in death of loosestrife plants

• Reproductive output of surviving plants is unaltered

• Regrowth in the following years

• Loosestrife often occurs around lakes, streams, and reservoirs where it may be difficult or impossible to flood

• May increase the area of seed dispersal and assist in new colonization

• May change community composition and threaten desired vegetation and wildlife

2. Fire

• The overwintering rootstock lies 2 cm below the soil surface, where it is insulated from the heat of a surface fire

• There is not enough heat to destroy the rootstock

• The plant can regenerate

• The moist soil is generally difficult for sustained fire

3. Replacement control

• Introduce a desired plant species that can compete with weed

• Limited value because the treatment (introducing new plant species to the environment) is potentially as disastrous to the community as the weed was in the first place

• Successful control of a heavy purple loosestrife infestation by repeatedly mowing, plowing, and planting reed canary grass. However, herbivory of reed canary grass by meadow voles may prevent permanent purple loosestrife displacement

• Japanese millet most promising replacement

Chemical Control

1. Glyphosate

• Nonselective herbicide for broadleaf and grasses

• Absorbed by the leaf surface and transported throughout the plant, including the roots

• Effective at relatively low concentrations and has a low potential for bioaccumulation

• In the next year's growing season, purple loosestrife seedling establishment was also affected by the timing of application the year before --the plots sprayed in June became reinfested, however the plots sprayed in July and August did not have purple loosestrife seedlings.

2. 2,4-D

• Selective control for broadleaf plants

• Complete control was not common and resprouting occurred across all treatments

• Developed resistance

3. Triclopyr

• Selectively controls brush and broad leaf plants, and can damage some grasses

• Spot spraying is recommended

• Not labeled for aquatic sites, but is used in road ditches for loosestrife control

• Effective treatment in reducing loosestrife biomass

• Seedlings were observed later the same season

• More efficient when applications are low to the ground and closer to the root

Concerns

• Potential non-target effects on wildlife and the plant community

• Direct application of the herbicide on a cut stem to reduce non-target effects. This would also increase the amount of chemical that reaches the rootstock.

• Cost

Biological control

Characteristics of purple loosestrife that make it an ideal candidate for biological control

• Introduced

• Perennial

• Not closely related to economically valuable plants

• Potential for doing serious damage over large areas of land

• Restricted to a specific and relatively stable habitat

• More or less continuous distribution

• Alternative means of control have been tried, but found to be inadequate and infeasible

• Empty feeding niche exists in North America

The natural enemies

More than 100 insect species have been found to be associated with purple loosestrife in Europe

Of these 14 species were determined to be host specific

Detailed ecological and host-specificity studies were recommended for 6 of the 14 species:

• Dasineura salicariaea: a gall producer

• Hylobius transversovittatus: a stem and root boring weevil

• Galerucella calmariensis and G. pusilla: two leaf-feeding beetles

• Nanophyes marmoratus and N. brevis: two weevils that feed on the ovaries and seeds

1. Dasineura salicariaea

• A cecidomyiid fly

• A gall producer

• Reduces purple loosestrife biomass by 75%

• Reduces seed production by 80%

• Not introduced into the United States

2. Hylobius transversovittatus

• Root-feeding weevil

• Reduced plant performance and a delay in flowering

• Adults feed on the leaf and stem tissue

• Larvae bore into the rootstock

• Pupal period varies from 5-15 months

• The total life cycle may last up to two years

• Released in the United States

3. Galerucella calmariensis and G. pusilla

• Most promising potential biological control agents

• Ranked first with high fecundity, widespread distribution, and high abundance

• Both leaf-feading beetles

• 50% defoliation

• Adults feed on plants until a high level of damage occurs, then they leave heavily damaged plants in search of unattacked plants

• Defoliated plants are less healthy and may be unable to flower

• Adult feeding is in an ishotholei pattern, leaving small holes in the center of the leaves

• Larval feeding strips the photosynthetic tissue from the leaf, causing damage at high frequency

• Releases began in 1992 as part of a biological control program

• The first releases were made in New York, Pennsylvania, Maryland, Virginia, Minnesota, Oregon, and Washington, as well as releases in Canada

• Successful establishment occurred at 25 of the 26 of the first field release sites

• Additional releases have been made throughout the Midwest

• Established across the northern United States

• Reduce loosestrife survival in the field by 33-66%

4. Nanophyes marmoratus and N. brevis

• Both flower feeding weevils

• Adult weevils feed on the leaf material

• When the flower buds develop the weevils copulate and oviposit within closed flower buds

• One egg per flower is oviposited

• The larva will consume the stamens, the petals, and the ovary

5. Myzus lythri

• A European aphid

• Not selected for release, but commonly found in the United States and Canada

• Influence on purple loosestrife is variable

• It is a host-alternating aphid spending the fall, winter, and spring on its primary host Prunus spp. and the summer on its alternate host Lythrum spp.

• Not specific to L. salicaria but to the entire genus

6. Laboratory investigations into a native pathogen are ongoing

Concerns

• Non-target feeding

M. Noxious Weed Status for Purple Loosestrife

• Many states are regulating the production, sale, and/or use of purple loosestrife.

• Listed as a noxious weed in 13 states

• Noxious status usually places the species under the State's pure seed surveillance and plant quarantine laws.

• In addition, in most States it qualifies the plant for existing weed control enforcement programs and funding.

Bibliography

A. Taxonomy

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

North Carolina State University. (1998) Information on wetlands. (http://h2osparc.wq.ncsu.edu/info/wetlands).

Shinners, L. H. (1953) Synopsis of the United States species of Lythrum (Lythraceae). Field Lab. 21:80-89.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

B. Geographical Distribution

Hulten, E. (1971) The circumpolar plants. 2. Almqvist & Wiksell, Stockholm. 463 pp.

Jones, M. A. (1976) Destination America. Holt, Rinehart & Winston, New York. 256 pp.

Malecki, R. A., B. Blossey, S. D. Hight & D. Schroeder. (1993) Biological control of purple loosestrife: a case for using insects as control agents, after rigorous screening, and for integrating release strategies with research. BioScience. 43: 680-686.

North Carolina State University. (1998) Information on wetlands. (http://h2osparc.wq.ncsu.edu/info/wetlands).

Piper, G.L. (1996) Biological control of the wetlands weed purple loosestrife (Lythrum salicaria) in the Pacific northwestern United States. Hydrobiologia. 340: 291-294.

Shinners, L. H. (1953) Synopsis of the United States species of Lythrum (Lythraceae). Field Lab. 21:80-89.

Skinner, L., W. J. Rendall & E. L. Fuge. (1994) Minnesota's Purple loosestrife program: history, findings, and management recommendations. Minnesota Department of Natural Resources. Special Publication 145: 1-25.

Stuckey, R. L. (1980) Distributional history of Lythrum salicaria (purple loosestrife) in North America. Bartonia. 47: 3-20.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Thompson, D. Q., R. L. Stuckey, and E. B. Thompson. (1987) Spread, impact, and control of purple loosestrife (Lythrum salicaria) in North American wetlands. United States Fish and Wildlife Service, Fish and Wildlife Research 2.

C. Biology

Abernethy, V.J. and N.J. Willby. (1999) Changes along a disturbance gradient in the density composition of propagule banks in floodplain aquatic habitats. Plant Ecology. 140: 177- 190.

Burdon, J.J. and D.R. Marshall. (1981) Biological control and the reproductive mode of weeds. Journal of Applied Ecology. 18: 649-658.

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Darwin, C. (1893) The different forms of flowers on plants of the same species. D. Appleton and Company, New York. viii + 352 pp.

Eckert, C.G., D. Manicacci, and S.C. H. Barrett. (1996) Frequency-dependent selection on morph ratios in tristylous Lythrum salicaria (Lythraceae). Heredity. 77: 581-588.

Eckert, C.G., D. Manicacci, and S.C.H. Barrett. (1996) Genetic drift and founder effect in native versus introduced populations of an invading plant, Lythrum salicaria (Lythraceae) Evolution. 50: 1512-1519.

Emery, S. L. & J. A. Perry. (1995) Aboveground biomass and phosphorus concentrations of Lythrum salicaria (purple loosestrife) and Typha spp. (cattail) in 12 Minnesota wetlands. American Midland Naturalist. 134: 394-399.

Farrar, J. (1989) Stemming the purple plague. Nebraska land. 67: 38-44.

Galatowitsch, S.M., N.O. Anderson, and P. D. Ascher. (1999) Invasiveness in wetland plants in temperate North America. Wetlands. 19: 733-755.

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

Mann, H. (1991) Purple loosestrife: a botanical dilemma. The Osprey. 22: 67-77.

North Carolina State University. (1998) Information on wetlands. (http://h2osparc.wq.ncsu.edu/info/wetlands).

O' Neil, P. (1999) Selection on flowering time: an adaptive fitness surface for nonexixtent character combinations. Ecology. 80: 806-820.

O'Neil, P. (1997) Natural Selection on Genetically Correlated Phenological characters in Lythrum salicaria L. (Lythraceae). Evolution. 51: 267-274.

Rawinski, T. J. (1982) The ecology and management of purple loosestrife (Lythrum salicaria L.) in central New York. M.S. thesis, Cornell University, Ithaca, N.Y. ix + 88 pp.

Rawinski, T. J., and R. A. Malecki. (1984) Ecological relationships among purple loosestrife, cattail and wildlife at the Montezuma National Wildlife Refuge. N.Y. Fish Game J. 31:81-87.

Shamsi, S. R. A., and F. H. Whitehead. (1974) Comparative eco-physiology of Epilobium hirsutum L. and Lythrum salicaria L. 1. General biology, distribution and germination. J. Ecol. 62:279-290.

Shinners, L. H. (1953) Synopsis of the United States species of Lythrum (Lythraceae). Field Lab. 21:80-89.

Skinner, L., W. J. Rendall & E. L. Fuge. (1994) Minnesota's Purple loosestrife program: history, findings, and management recommendations. Minnesota Department of Natural Resources. Special Publication 145: 1-25.

Stevens, K.J., R. L. Peterson, and G. R. Stephenson. (1997) Vegetative propagation and the tissues involved in lateral spread of Lythrum salicaria. Aquatic Botany. 56: 11-24.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Treberg, M.A. and B.C. Husband. (1999) Relationship between the abundance of Lythrum salicaria (purple loosestrife) and plant species richness along the Bar River, Canada. Wetlands. 19: 118-123.

Venecz, J.I. and L. W. Aarssen. (1998) Effects of shoot apex removal in Lythrum salicaria (Lythraceae): Assessing the costs of reproduction and apical dominance. Annals of Botany Fennici: 35: 101-111.

Welling, C. H. and Becker, R. L. (1990) Seed bank dynamics of Lythrum salicaria L.: implications for control of this species in North America. Aquatic Botany 38:303-309.

Weiher, E., I.C. Wisheu, P.A. Keddy and D.R.J. Moore. (1996) Establishment, persistence, and management implications of experimental wetland plant communities. Wetlands. 16: 208-218.

Willis, A.J., M.B. Thomas, and J.C. Lawton. (1999) Is the increased vigour of invasive weeds explained by a trade-off between growth and herbivore resistance? Oecologia. 120: 632-640.

D. Dispersal and Spread

Balogh, G. R. & T. A. Bookhout. (1989) Remote detection and measurement of purple loosestrife stands. Wildlife Society Bulletin. 17:66-67.

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Edwards, K.R., J. Kvet and M.S. Adams. (1999) Comparison of Lythrum salicaria L. study sites in the midwest U.S. and central Europe. Ekologia (Bratislava). 18: 113-124.

Galatowitsch, S.M., N.O. Anderson, and P. D. Ascher. (1999) Invasiveness in wetland plants in temperate North America. Wetlands. 19: 733-755.

Loos, A. and D. Ragsdale. (1998) Biological Control of Purple loosestrife: a guide for rearing leaf-feeding beetles. University of Minnesota Extension. St. Paul, MN.

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

Mal, T. K., J. Lovett-Doust, and L. Lovett-Doust. (1997) Effect of soil moisture and fertilizer application on clonal growth and reproduction in a tristylous weed, Lythrum salicaria. Canadian Journal of Botany. 75: 46-60.

Malecki, R. A., B. Blossey, S. D. Hight & D. Schroeder. (1993) Biological control of purple loosestrife: a case for using insects as control agents, after rigorous screening, and for integrating release strategies with research. BioScience. 43: 680-686.

Mann, H. (1991) Purple loosestrife: a botanical dilemma. The Osprey. 22: 67-77.

Mullin, B.H. (1998) The biology and management of purple loosestrife (Lythrum salicaria). Weed Technology. 12: 397-401.

North Carolina State University. (1998) Information on wetlands. (http://h2osparc.wq.ncsu.edu/info/wetlands).

Rawinski, T. J. (1982) The ecology and management of purple loosestrife (Lythrum salicaria L.) in central New York. M.S. thesis, Cornell University, Ithaca, N.Y. ix + 88 pp.

Smith, H.A., W.S. Johnson, J.S. Shonkwiler and S.R. Swanson. (1999) The implications of variable or constant expansion rates in invasive weed infestations. Weed Science. 47: 62-66.

Stevens, K.J., R. L. Peterson, and G. R. Stephenson. (1997) Vegetative propagation and the tissues involved in lateral spread of Lythrum salicaria. Aquatic Botany. 56: 11-24.

Stuckey, R. L. (1980) Distributional history of Lythrum salicaria (purple loosestrife) in North America. Bartonia. 47: 3-20.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Thompson, D. Q., R. L. Stuckey, and E. B. Thompson. (1987) Spread, impact, and control of purple loosestrife (Lythrum salicaria) in North American wetlands. United States Fish and Wildlife Service, Fish and Wildlife Research 2.

Venecz, J.I. and L. W. Aarssen. (1998) Effects of shoot apex removal in Lythrum salicaria (Lythraceae): Assessing the costs of reproduction and apical dominance. Annals of Botany Fennici: 35: 101-111.

Welling, C. H. and Becker, R. L. (1990) Seed bank dynamics of Lythrum salicaria L.: implications for control of this species in North America. Aquatic Botany 38:303-309.

E. Seedling Establishment

Emery, S. L. & J. A. Perry. (1995) Aboveground biomass and phosphorus concentrations of Lythrum salicaria (purple loosestrife) and Typha spp. (cattail) in 12 Minnesota wetlands. American Midland Naturalist. 134: 394-399.

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

Mal, T. K., J. Lovett-Doust, and L. Lovett-Doust. (1997) Effect of soil moisture and fertilizer application on clonal growth and reproduction in a tristylous weed, Lythrum salicaria. Canadian Journal of Botany. 75: 46-60.

Rawinski, T. J. (1982) The ecology and management of purple loosestrife (Lythrum salicaria L.) in central New York. M.S. thesis, Cornell University, Ithaca, N.Y. ix + 88 pp.

Rawinski, T. J., and R. A. Malecki. (1984) Ecological relationships among purple loosestrife, cattail and wildlife at the Montezuma National Wildlife Refuge. N.Y. Fish Game J. 31:81-87.

Shamsi, S. R. A., and F. H. Whitehead. (1974) Comparative eco-physiology of Epilobium hirsutum L. and Lythrum salicaria L. 1. General biology, distribution and germination. J. Ecol. 62:279-290.

Shipley, B. and M. Parent. (1991) Germination responses of 64 wetland species in relation to seed size, minimum time to reproduction and seedling relative growth rate. Functional Ecology. 5: 111-118.

Templer, P., S. Findlay and C. Wigand. (1998) Sediment chemistry associated with native and non-native emergent macrophytes of a Hudson River marsh ecosystem. Wetlands. 18: 70-78.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Weihe, P.E. and R. K. Neely. (1997) The effects of shading on competition between purple loosestrife and broad-tailed cattail. Aquatic Botany. 59: 127-138.

Weiher, E., I.C. Wisheu, P.A. Keddy and D.R.J. Moore. (1996) Establishment, persistence, and management implications of experimental wetland plant communities. Wetlands. 16: 208-218.

F. Stability of Purple Loosestrife Stands

Edwards, K.R., J. Kvet and M.S. Adams. (1999) Comparison of Lythrum salicaria L. study sites in the midwest U.S. and central Europe. Ekologia (Bratislava). 18: 113-124.

Faeth, S.H. (1992) Interspecific and intraspecific interactions via plant responses to folivory: an experimental field test. Ecology. 73: 1802-1813.

Grevstad, F.S. and A.L. Herzig. (1997) Quantifying the effects of distance and conspecifics on colonization: experiments and models using the loosestrife leaf beetle, Galerucella calmariensis. Oecologia. 110: 60-68.

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

Moody, M. E. and R. N. Mack. (1988) Controlling the spread of plant invasions: the importance of nascent foci. Journal of Applied Ecology. 25: 1009-1021.

Rawinski, T. J. (1982) The ecology and management of purple loosestrife (Lythrum salicaria L.) in central New York. M.S. thesis, Cornell University, Ithaca, N.Y. ix + 88 pp.

Smith, H.A., W.S. Johnson, J.S. Shonkwiler and S.R. Swanson. (1999) The implications of variable or constant expansion rates in invasive weed infestations. Weed Science. 47: 62-66.

Templer, P., S. Findlay and C. Wigand. (1998) Sediment chemistry associated with native and non-native emergent macrophytes of a Hudson River marsh ecosystem. Wetlands. 18: 70-78.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Weiher, E., I.C. Wisheu, P.A. Keddy and D.R.J. Moore. (1996) Establishment, persistence, and management implications of experimental wetland plant communities. Wetlands. 16: 208-218.

G. Habitat

Abernethy, V.J. and N.J. Willby. (1999) Changes along a disturbance gradient in the density composition of propagule banks in floodplain aquatic habitats. Plant Ecology. 140: 177- 190.

Agren, J. (1996) Population size, pollinator limitation, and seed set in the self-incompatible herb Lythrum salicaria. Ecology. 77: 1779-1790.

Grevstad, F.S. and A.L. Herzig. (1997) Quantifying the effects of distance and conspecifics on colonization: experiments and models using the loosestrife leaf beetle, Galerucella calmariensis. Oecologia. 110: 60-68.

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

Mann, H. (1991) Purple loosestrife: a botanical dilemma. The Osprey. 22: 67-77.

H. Purple Loosestrife Look Alikes

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Loos, A. and D. Ragsdale. (1998) Biological Control of Purple loosestrife: a guide for rearing leaf-feeding beetles. University of Minnesota Extension. St. Paul, MN.

I. Horticulture Varieties

Anderson, N.O. and P. D. Ascher. (1993) Male and female fertility of loosestrife (Lythrum) cultivars. Journal of American Horticulture Science 118: 851-858.

Cortilet, A. (1998) Evaluation of natural enemies reared and released for the biological control of purple loosestrife. Master's Thesis. Agronomy, Iowa State University, Ames, IA.

Mal, T.K., J. Lovett-Doust, L. Lovett-Doust, and G.A. Mulligan. (1992) The biology of Canadian weeds. 100. Lythrum salicaria. Canadian Journal of Plant Science. 72: 1305-1330.

Ottenbreit, K.A. and R.J. Stanniforth. (1994) Crossability of naturalized and cultivated Lythrum taxa. Canadian Journal of Botany. 72: 337-341.

Strefeler, M.S., E. Darmo, R.L. Becker, and E. J. Katovich. (1996) Isozyme variation in cultivars of purple loosestrife (Lythrum sp.). HortScience. 31:279-282.

Wade, D. E. (1985) Ethics and the prairie movement. Nat. Study 38:35,34.

J. Why is it a Problem?

Anderson, M. G. (1995) Interactions Between Lythrum salicaria and Native Organisms: A Critical Review. Environmental Management. 19: 225-231.

Barbour, J. G. and E. Kiviat. (1997) Introduced purple loosestrife as host of native Saturniidae (Lepidoptera). The Great Lakes Entomologist. 30: 115-122.

Bury, R. B. (1979) Review of the ecology and conservation of the bog turtle, Clemmys muhlenbergii. U.S. Fish Wildl. Serv., Spec. Sci. Rep.--Wildl. 219. 9 pp.

Coddington, J., and K. G. Field. (1978) Rare and endangered vascular plant species in Massachusetts. Committee for Rare and Endangered Species of the New England Botanical Club, Cambridge, Mass. 62 pp.

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Cortilet, A. (1998) Evaluation of natural enemies reared and released for the biological control of purple loosestrife. Master's Thesis. Agronomy, Iowa State University, Ames, IA.

Diehl, J.K., N.J. Holliday, C.J. Lingren, and R.E. Roughley. (1997) Insects associated with purple loosestrife, Lythrum salicaria L., in southern Manitoba. 129: 937-948.

Emery, S. L. & J. A. Perry. (1995) Aboveground biomass and phosphorus concentrations of Lythrum salicaria (purple loosestrife) and Typha spp. (cattail) in 12 Minnesota wetlands. American Midland Naturalist. 134: 394-399.

Faeth, S.H. (1992) Interspecific and intraspecific interactions via plant responses to folivory: an experimental field test. Ecology. 73: 1802-1813.

Farrar, J. (1989) Stemming the purple plague. Nebraska land. 67: 38-44.

Fernald, M. L. (1940) The problem of conserving rare native plants. Smithson. Inst. Annu. Rep. (1939):375-391.

Gabor, T. S., T. Haagsma, and H. R. Murkin. (1996) Wetland plant responses to varying degrees of purple loosestrife removal in Southeastern Ontario, Canada. Wetlands. 16:95-98.

Hager, H.A. and K. D. McCoy. (1998) The implications of accepting untested hypotheses: review of the effects of purple loosestrife (Lythrum salicaria) in North America. Biodiversity and Conservation. 7: 1069-1079.

Johansson, M. E. and P. A. Keddy. (1991) Intensity and asymmetry of competition between plant pairs of different degrees of similarity: an experimnetal study on two guilds of wetland plants. Oikos. 60: 27-34.

Kiviat, E. (1978) American Goldfinch nests in purple loosestrife. Wilson Bulletin. 108: 182-186.

Malecki, R. A., B. Blossey, S. D. Hight & D. Schroeder. (1993) Biological control of purple loosestrife: a case for using insects as control agents, after rigorous screening, and for integrating release strategies with research. BioScience. 43: 680-686.

Moore, D.R. J. and P.A. Keddy. (1989) Conservation of infertile wetlands: priorities and management. In M.J. Bardecki and N. Patterson. (Eds. ) Wetlands: inertia or momentum. Proceedings of Conference, Ryerson Polytechnical Institute, Toronto, ON. Oct. 21-22, 1988. Federation of Ontario Naturalists, Don Mills, ON.

Rawinski, T. J., and R. A. Malecki. (1984) Ecological relationships among purple loosestrife, cattail and wildlife at the Montezuma National Wildlife Refuge. N.Y. Fish Game J. 31:81-87.

Shipley, B. and M. Parent. (1991) Germination responses of 64 wetland species in relation to seed size, minimum time to reproduction and seedling relative growth rate. Functional Ecology. 5: 111-118.

Stein, J. (2000) Purple loosestrife declared public enemy. Mississippi Monitor. IV (1): 11.

Stoudt, J. H. (1982) Habitat use and productivity of canvasbacks in southwestern Manitoba, 1961-72. U.S. Fish Wildl. Serv., Spec. Sci. Rep.--Wildl. 248. iv + 31 pp.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Thompson, D. Q., R. L. Stuckey, and E. B. Thompson. (1987) Spread, impact, and control of purple loosestrife (Lythrum salicaria) in North American wetlands. United States Fish and Wildlife Service, Fish and Wildlife Research 2.

Thompson, D., and B. Yates. (1985) The purple peril. Wyo. Wildl. 49:14-15.

Treberg, M.A. and B.C. Husband. (1999) Relationship between the abundance of Lythrum salicaria (purple loosestrife) and plant species richness along the Bar River, Canada. Wetlands. 19: 118-123.

Wade, D. E. (1985) Ethics and the prairie movement. Nat. Study 38:35,34.

Weihe, P.E. and R. K. Neely. (1997) The effects of shading on competition between purple loosestrife and broad-tailed cattail. Aquatic Botany. 59: 127-138.

Whitt, M.B., H.H. Prince, And R. R. Cox, Jr. (1999) Avian use of purple loostrife dominated habitat relative to other vegetation types in a Lake Huron wetland complex. Wilson Bulletin. 111: 105-114.

Willis, A.J., M.B. Thomas, and J.C. Lawton. (1999) Is the increased vigour of invasive weeds explained by a trade-off between growth and herbivore resistance? Oecologia. 120: 632-640.

K. Benefits

Farrar, J. (1989) Stemming the purple plague. Nebraska land. 67: 38-44.

Grieve, M. (1923) Bee-plants and their honey.--VII. Bee World 4:196.

Malecki, R. A., B. Blossey, S. D. Hight & D. Schroeder. (1993) Biological control of purple loosestrife: a case for using insects as control agents, after rigorous screening, and for integrating release strategies with research. BioScience. 43: 680-686.

Pellett, M. (1977) Purple loosestrife spreads down river. American Bee Journal. 117: 214-215.

Pellett, M. (1956) From the honey plant gardens. Am. Bee J. 96:198-199.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

L. Control

Cortilet, A. (1998) Evaluation of natural enemies reared and released for the biological control of purple loosestrife. Master's Thesis. Agronomy, Iowa State University, Ames, IA.

Friesen, G. (1966) Aquatic weed control studies in Manitoba. North Cent. Weed Control Conf. 21:42-43.

Gabor, T. S., T. Haagsma, and H. R. Murkin. (1996) Wetland plant responses to varying degrees of purple loosestrife removal in Southeastern Ontario, Canada. Wetlands. 16:95-98.

Gabor, T. S. and H. R. Murkin. (1990) Effects of clipping purple loosestrife seedlings during a simulated wetland drawdown. Journal of Aquatic Plant Management. 28: 98-100.

Ghersa, C.M. and M. L. Roush. (1993) Searching for solutions to weed problems. BioScience. 43: 104-109.

Haworth-Brockman, M.J., H.R. Murkin, R.T. Clay, and E. Armson. (1991) Effects of underwater clipping of purple loosestrife in a southern Ontario wetland. Journal of Aquatic Plant Management. 29: 117-118.

Leppla, N. C. (1996) Environmentally friendly methods for reducing the damage caused by exotic weeds in natural habitats: conflicts of interest, safeguards and national policy. Castanea. 61:214-225.

Mal, T.K., J. Lovett-Doust, and L. Lovett-Doust. (1997) Time-dependent competitive displacement of Typha angustifolia by Lythrum salicaria. Oikos. 79: 26-33.

Moody, M. E. and R. N. Mack. (1988) Controlling the spread of plant invasions: the importance of nascent foci. Journal of Applied Ecology. 25: 1009-1021.

Mullin, B.H. (1998) The biology and management of purple loosestrife (Lythrum salicaria). Weed Technology. 12: 397-401.

Skinner, L., W. J. Rendall & E. L. Fuge. (1994) Minnesota's Purple loosestrife program: history, findings, and management recommendations. Minnesota Department of Natural Resources. Special Publication 145: 1-25.

Smith, R.H. (1964) Experimental control of purple loosestrife (Lythrum salicaria). New York Fish and Game Journal. 11: 35-46.

Smith, L. S. (1959) Some experiences with control of purple loosestrife at the Montezuma National Wildlife Refuge. Proc. Northeast. Weed Control Conf. 13:333-336.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Thompson, D. Q., R. L. Stuckey, and E. B. Thompson. (1987) Spread, impact, and control of purple loosestrife (Lythrum salicaria) in North American wetlands. United States Fish and Wildlife Service, Fish and Wildlife Research 2.

Weiher, E., I.C. Wisheu, P.A. Keddy and D.R.J. Moore. (1996) Establishment, persistence, and management implications of experimental wetland plant communities. Wetlands. 16: 208-218.

Chemical Control

Gardner, S. C. and C. E. Grue. (1996) Effects of Rodeo and Garlon 3A on nontarget wetland species in central Washington. Environmental Toxicology and Chemistry. 15: 441-451.

Katovich, E. J., R. L. Becker and B.D. Kinkaid. (1996) Influence of nontarget neighbors and spray volume retention and efficacy of Triclopyr in purple loosestrife (Lythrum salicaria). Weed Science. 44: 143-147.

McKeon, W. H. (1959) A preliminary report on the use of chemical herbicides to control purple loosestrife (Lythrum salicaria) on a small marsh. Proc. Northeast. Weed Control Conf. 13:329-332.

Nelson, L.S., K.D. Getsinger and J.E. Freedman. (1996) Efficacy of Triclopyr on purple loosestrife and associated wetland vegetation. Lournal of Aquatic Plant Management. 34: 72-74.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Wahlers, R. L., J.D. Burton, E.P.. Maness, and W.A. Skroch. (1997) A stem cut and blade delivery method of herbicide application for weed control. Weed Science. 45: 829-832.

Biological Control

Batra, S.W.T., D. Schroeder, P.E. Boldt, and W. Mendl. (1986) Insects associated with purple loosestrife (Lythrum salicaria) in Europe. Proceedings of the Entomological Society in Washington. 88: 748-759.

Blossey, B. (1995) A comparison of various approaches for evaluating potential biological control agents using insects on Lythrum salicaria. Biological Control. 5: 113-122.

Blossey, B. (1995) Coexistence of two leaf-feeding beetles in the same fundamental niche. Distribution, adult phenology and oviposition. Oikos. 74: 225-234.

Blossey, B. (1995) Impact of Galerucella pusilla and G. calmariensis (Coleoptera: Chrysomelidae) on field populations of purple loosestrife (Lythrum salicaria ) Proceedings of the Eighth International Symposium on Biological Control of Weeds 2-7 February 1992, Lincoln University, Canterbury, New Zealand. Delfosse, E.S. and R.R. Scott (eds.) DSIR/CSIRO, Melbourne, pp. 27-31.

Blossey, B. and T. R. Hunt. (1999) Mass rearing methods for Galerucella calmariensis and G. pusilla (Coleoptera: Chrysomelidae), biological control agents of Lythrum salicaria (Lythraceae). Journal of Economic Entomology. 92: 325-334.

Blossey, B. and M. Schat. (1997) Performance of Galerucella calmariensis (Coleoptera: Chrysomelidae) on different North American populations of purple loosestrife. Environmental Entomology. 26: 439-445.

Blossey, B. & D. Schroeder. (1995) Host specificity of three potential biological weed control agents attacking flowers and seeds of Lythrum salicaria (Purple Loosestrife). Biological Control. 5: 47-53.

Blossey, B., D. Schroeder, S. D. Hight & R. A. Malecki. (1994) Host Specificity and Environmental Impact of Two Leaf Beetles (Galerucella calmariensis and G. pusilla) for Biological Control of Purple loosestrife (Lythrum salicaria). Weed Science. 42: 134-140.

Blossey, B., D. Schroeder, S. D. Hight & R. A. Malecki. (1994) Host Specificity and Environmental Impact of the weevil Hylobius transversovittatus, a biological control agent of purple loosestrife (Lythrum salicaria). Weed Science. 42: 128-133.

Blossey, B. & D. Schroeder. (1988) Study and Screening of potential biological control agents of purple loosestrife (Lythrum salicaria L.). CAB International Institute of BioControl. First Report.

Burdon, J.J. and D.R. Marshall. (1981). Biological control and the reproductive mode of weeds. Journal of Applied Ecology. 18: 649-658.

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Corrigan, J.E., D. L. Mackenzie and L. Simser. (1998) Field observations of non-target feeding by Galerucella calmariensis [Coleoptera: Chrysomelidae], an introduced biological control agent of purple loosestrife, Lythrum salicaria [Lythraceae]. Proceedings of the Entomological Society of Ontario. 129: 99-106.

Cortilet, A. (1998) Evaluation of natural enemies reared and released for the biological control of purple loosestrife. Master's Thesis. Agronomy, Iowa State University, Ames, IA.

Gardner, D.E., C.W. Smith, and G.P. Markin. (1995) Biological control of alien plants in natural areas of Hawaii. pp. 35-40 In Proceedings of the Eighth international Symposium on biolog ical control of weeds 2-7 February 1992, Lincoln University, Canterbury, New Zealand. Delfosse, E.S. and R. R. Scott [eds.]. DSIR/CSIRO, Melbourne.

Harris, P. (1991) Classical biocontrol of weeds: its defination, selection of effective agents, and administrative-political problems. Canadian Entomologist. 123: 827-849.

Hight, S. D., B. Blossey, J. Laing, R. Declerck-Floate. (1995) Establishment of insect biological control agents from Europe against Lythrum salicaria in North America. Environmental Entomology. 24: 967-977.

Howarth, F. G. (1991) Environmental impacts of classical biological control. Annual Review of Entomology. 36: 485-509.

Katovich, E. J., R. L. Becker and D. W. Ragsdale. (1999) Effect of Galerucella spp. on survival of purple loosestrife (Lythrum salicaria) roots and crowns. Weed Science. 47: 360-365.

Keese, M. C. (1997) Does escape to enemy-free space explain host specialization in two closely related leaf-feeding beetles (Coleoptera: Chrysomelidae)? Oecologia. 112: 81-86.

Lingren, C.J., (1997) Oviposition site preference of Galerucella calmariensis and G. pusilla, biological control agents of purple loosestrife (Lythrum salicaria). Weed Technology. 11: 824-827.

Loos, A. and D. Ragsdale. (1998) Biological Control of Purple loosestrife: a guide for rearing leaf-feeding beetles. University of Minnesota Extension. St. Paul, MN.

Malecki, R. A., B. Blossey, S. D. Hight & D. Schroeder. (1993) Biological control of purple loosestrife: a case for using insects as control agents, after rigorous screening, and for integrating release strategies with research. BioScience. 43: 680-686.

Malecki, R. A., T. J. Rawinski.(1985) New Methods for Controllong Purple Loosestrife. New York Fish and Game Journal. 32: 9-19.

Manguien, S., R. White, B. Blossey & S. Hight. (1996) Genetics, Taxonomy, and Ecology of Certain Species of Galerucella (Coleoptera: Chrysomelidae). Annals of the Entomological Society of America. 86: 397-407.

Murdoch, W.M., J. Chesson, and P.L. Chesson. (1985) Biological control in theory and practice. American Naturalist 125: 344-366.

Nechols, J. R., J. J. Obrycki, C. A. Tauber & M. J. Tauber. (1996) Potential impact of natural enemies on Galerucella spp. (Coleoptera: Chrysomelidae) imported for biological control of Purple Loosestrife: a field evaluation. Biological Control. 7: 60-66.

North Carolina State University. (1998) Information on wetlands. (http://h2osparc.wq.ncsu.edu/info/wetlands).

Notzold, R., B. Blossey, and E. Newton. (1998) The influence of below ground herbivory and plant competition on growth and biomass allocation of purple loosesstrife. Oecologia. 113: 82-93.

Nyvall, R. F. and A. Hu. (1997) Laboratory evaluation of indidenous North American fungi for biological control of purple loosestrife. Biological Control. 8: 37-42.

Piper, G.L. (1996) Biological control of the wetlands weed purple loosestrife (Lythrum salicaria) in the Pacific northwestern United States. Hydrobiologia. 340: 291-294.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

Voegtlin, D.J. (1995) Potential of Myzus lythri (Homoptera: Aphididae) to influence growth and development of Lythrum salicaria (Myrtiflorae: Lythraceae). Biological Control. 24: 724-729.

White, R. E. (1996) Leaf Beetles as Biological Control Agents Against Injurious Plants in North America. Chrysomelidae Biology, vol.2: Ecological Studies. Edited by P.H.A. Jolivet and M. L. Cox. 373-399.

Wiebe A. and J. Obrycki. (1998) Egg predation of Galerucella calmariensis and G. pusilla: Biological control agents of purple loosestrife (Lythrum salicaria).North Central Branch Entomol. Soc. Amer. Meeting Des Moines, IA. March 1999. Abstract (http://www.ent.iastate.edu/entsoc/ncb 99/prog/abs/081.html).

M. Noxious Weed Status

Cornell University. (1998) Biological Control: A guide to natural enemies in North America. (http://www.nysaes.cornell.edu).

Leppla, N. C. (1996) Environmentally friendly methods for reducing the damage caused by exotic weeds in natural habitats: conflicts of interest, safeguards and national policy. Castanea. 61:214-225.

Loos, A. and D. Ragsdale. (1998) Biological Control of Purple loosestrife: a guide for rearing leaf-feeding beetles. University of Minnesota Extension. St. Paul, MN.

Thompson, D. Q., R. L. Stuckey, E. B. Thompson. (1985) Spread, Impact, and Control of Purple Loosestrife (Lythrum salicaria ) in North American Wetlands. U.S. Fish and Wildlife Service. 55 pages.Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/1999/loosstrf/loosstrf.htm (Version 04JUN99).

N. Invasive Species (General)

Bright, C. (1995) Bio-invasions: the spread of exotic species. World Watch. July/August: 10-19.

Cheater, M. (1992) Alien invasion. Nature Conservancy. Sept/Oct: 25-29.

Devine, R. (1994) Botanical barbarians. January/February: 50-57, 71.

Lindgren, C. (1996) X-files: an invasive alien. Purple Loosestrife Infocentre Newsletters. Winter 1-4.

Malakoff, D. (1999) Biological invaders. Science. 285: 1834-1843.

Randall, J.M. (1996) Weed Control for the preservation of biological diversity. Weed Technology. 10:370-383.

Reschke, P. (1990) The invader. Angler & Hunter. Apr. 16-18.

Westbrooks, R. (1998) Invasive plants, changing the landscape of America: Fact book. Federal Interagency Committee for the Management of Noxious and Exotic Weeds (FICMNEW), Washington, D.C.

Williams, T. (1994) Invasion of the Aliens. Audubon. Sept/Oct: 24-32.