Plant Assessment Form

Lythrum salicaria

Common Names: purple loosestrife

Evaluated on: 22-Jul-04

List committee review date: 27/08/2004

Re-evaluation date:

Evaluator(s)

Carri Pirosko/Associate Agricultural Biologist
Noxious Weed Program, California Department of Food and Agriculture
20235 Charlanne Drive, Redding CA 96002
530-545-9119
cpirosko@cdfa.ca.gov
Joseph M. DiTomaso
University of California
Weed Science Program, Robbins Hall, Davis, CA 95616
530-754-8715
ditomaso@vegmail.ucdavis.edu

List commitee members

John Randall
Cynthia Roye
Alison Stanton
Peter Warner
Jake Sigg
Joe DiTomaso

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? High
Alert Status? No Alert
Documentation? 4 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes A Reviewed Scientific Publication
Impact?
Four-part score AAAC Total Score
A
1.2 ?Impact on plant community A. Severe Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels A. Severe Reviewed Scientific Publication
1.4 ?Impact on genetic integrity C. Minor/Low Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Reviewed Scientific Publication
Invasiveness?
Total Points
19 Total Score A
2.2 ?Local rate of spread with no management A. Increases rapidly Reviewed Scientific Publication
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly Other Published Material
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal A. High Reviewed Scientific Publication
2.6 ? Potential for natural long-distance dispersal A. Frequent Reviewed Scientific Publication
2.7 ?Other regions invaded A. Invades 3 or more ecological types Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Other Published Material

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? A Reviewed Scientific Publication
Identify ecosystem processes impacted:

nutrient dynamics; sedimentation; hydrologic regimes; light availability Interferes with wetland functions, including productivity and nutrient cycling; Leaves rapid decay rate results in release of significant amounts of NH4+ and PO43-; Dramatic changes in the physical as well as the trophic structure of wetland habitat; Leads to altered wetland function, chemistry and function; inpedes natural water flow causing increased silt deposition and reduction in water quality; decreases storage capacities of impounded waterbodies; solid stands block out 100% light from underneath canopy.


Sources of information:

Emery , S.L. and J.A. Perry, 1996. Decomposition rates and phosphorus concentration of purple loosestrife and cattail in 14 Minnesota wetlands. Hydrobiologia 323(2):129-138; Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp. Malecki, R.A., B. Blossey, S.D. Hight, D. Schroeder, L.T. Kok, and J.R. Coulson, 1993. Biological control of purple loosestrife. Bioscience 43(10):680-85.


Question 1.2 Impact on plant community composition,
structure, and interactions?
A Reviewed Scientific Publication
Identify type of impact or alteration:

Formation of stand dominated by loosestrife; occlusion of native canopy; has significantly reduced native species in other states In many states, loosestrife makes up more than 50% of the biomass of emergent vegetation causing canopy closure that results in a virtual biological "desert" underneath;

Has jeopardized various threatened and endangered native wetland plants and wildlife such as local bulrush (Scirpus longii) in Massachusettes, rare inland populations of dwarf spike rush (Eleocharis parvula) in New York, native flatsedge (Cyperus erythrorhizos), and bog turtle (Clemmys muhlenbergi) in the northeastern United States. Diverse wildlife and wetland vegetation, including Delta special status plant species and listed wetland dependent species would similarly be jeopardized.


Sources of information:

Rawinski, T.J. 1982. The ecology and of purple loosestrife in New York. Master's thesis, Cornell Univ.; Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp. Malecki, R.A., B. Blossey, S.D. Hight, D. Schroeder, L.T. Kok, and J.R. Coulson, 1993. Biological control of purple loosestrife. Bioscience 43(10):680-85. Skinner, L.C., Rendall, W.J., and Fuge, E.L., 1994. Minnesota's purple loosestrife program: history, findings, and management recommendations. Minn. Dept. Nat. Res. Special Publ. 145:1-27.


Question 1.3 Impact on higher trophic levels? A Reviewed Scientific Publication
Identify type of impact or alteration:

reduction and impact to nesting and foraging sites; cover for native animals; threatening to existing native wildlife and waterfoul species The rapid decay rateof purple loosestrife leaves has been shown to supply detritus to the ecosystem in the Autumn, whereas a much slower decay rate of resident vegetation supplies detritus throughout the winter and early spring- affecting juvenile salmon food webs; submersed terrestrial vegetation provides habitat for spawning and zooplankton critical to early fish survival- this is crowded-out by the establishment of loosestrife; dramatic changes in the trophic structure of wetland habitat has threatened the following wildlife species: Canada goose, wood duck, mallard, terns, canvasback, and sandhill cranes across the U.S.


Sources of information:

Coddington, J. and K.G. Field, 1987. Rare and Endangered vascular plant species in Massachusetts. New England Botanical Club, Cambridge, Massachussetts. Malecki, R.A., B. Blossey, S.D. Hight, D. Schroeder, L.T. Kok, and J.R. Coulson, 1993. Biological control of purple loosestrife. Bioscience 43(10):680-85. Skinner, L.C., Rendall, W.J., and Fuge, E.L., 1994. Minnesota's purple loosestrife program: history, findings, and management recommendations. Minn. Dept. Nat. Res. Special Publ. 145:1-27.


Question 1.4 Impact on genetic integrity? C Reviewed Scientific Publication

Some evidence of hybridization with cultivars in other states; less known in California, but potential exists based on work out of the eastern U.S. Many cultivars; can hybridize between cultivars; Introduction of ornamental plants of purple loosestife, wand loosestrife, and hybrid crosses increases its spread; Wand lythrum (Lythrum virgatum L.) a closely related species often hydridies with L. salicaria


Sources of information:

Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp; Mullin, B H., 1998. The Biology and of Purple Loosestrife (Lythrum salicaria). Weed Technology, vol. 12:397-401; Anderson, N.O. and P.D. Ascher, 1993. Male and Female Fertility of Loosestrife (Lythrum) Cultivars. J. Amer. Soc. Hort. Sci 118(6):851-858.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
A Reviewed Scientific Publication
Describe role of disturbance:

anthropogenic disturbances such as: gardening near waterways, altering hydrology/irrigation, roads and trails, construction spread purple loosestrife; natural disturbance such as: flooding and native animal activities (birds flying to distant locations away from a source) spread purple loosestrife. Purple loosestrife usually needs some disturbance (anthropogenic or natural) to invade an area, to a lesser extent it can invade "intact" plant communites.


Sources of information:

Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp.;


Question 2.2 Local rate of spread with no management? A Reviewed Scientific Publication
Describe rate of spread:

In other states, purple loosestrife has spread very rapidly, doubling within 10 years; The estimated spread of purple loosestrife between 1940 and 1980 has been estimated to be 1,160 km2/yr; In California the rate of spread has proceeded more slowly in most areas. Reports of several California infested sites increasing in size dramatically increased in the late 1980's/early 1990s. With a catalyst, e.g. flood event, spread can happen very rapidly, but without such disturbances, spread is more gradual overall.


Sources of information:

In other states, rate of spread documentation: Mitich, L. W., 1999. Intriguing World of Weeds, Purple Loosestrife, Lythrum salicaria, L. Weed Technology Vol. 13:843:846; Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp.;

In California: Observations by County Ag Offices and California Dept. of Food and Agriculture District Biologists.


Question 2.3 Recent trend in total area infested within state? B Other Published Material
Describe trend:

Increasing, but less rapidly. Statewide, purple loosestrife has yet to invade many areas; in areas where purple loosestrife exists in California, the rate of spread has been gradual and steady.


Sources of information:

California Department of Food and Agriculture Purple Loosestrife Program documents, reports, grant proposals, and mapping documentation.


Question 2.4 Innate reproductive potential? A Reviewed Scientific Publication
Describe key reproductive characteristics:

Spreads primarily by seed, resprouting of perennial crowns, and also by fragments washing down stream Can produce flower stalks within first year; produces up to 300,000 seed/stalk or up to 24 billion seed/acre; produces seed every year; can flower and produce seed throughout late spring into fall; seed can last greater than 3 years in the soil; resprouts readily when cut/mowed


Sources of information:

Mullin, B H., 1998. The Biology and of Purple Loosestrife (Lythrum salicaria). Weed Technology, vol. 12:397-401; personal observation; ancedotal; personal observation; ancedotal; Missouri Vegetation Management Manual, Tim Smith, Natural History Division; personal observation; ancedotal


Question 2.5 Potential for human-caused dispersal? A Reviewed Scientific Publication
Identify dispersal mechanisms:

numerous opportunities to spread via human-caused dispersal Brand new infestations likely to be from a gardener who planted loosestrife near a flowing water or pond situation; purple loosestrife can still be found for sale in nurseries (it is pulled off the shelf when found by county ag Dep't's) and can also be purchased on the internet; spreads along drainage/canal systems; can be transported on boats and in soil moved from site to site; BUT primary mode is through gardening/nursery


Sources of information:

Mullin, B H., 1998. The Biology and of Purple Loosestrife (Lythrum salicaria). Weed Technology, vol. 12:397-401; personal observation; ancedotal; personal observation; ancedotal


Question 2.6 Potential for natural long-distance dispersal? A Reviewed Scientific Publication
Identify dispersal mechanisms:

Frequently thought to be spread via long-distance dispersal, no other explanation for some remote sites waterfowl and small mammals thought to carry the tiny seed of their feathers/fur; spreads by seed and fragments via water


Sources of information:

Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp.; Missouri Vegetation Management Manual, Tim Smith, Natural History Division; Mullin, B H., 1998. The Biology and of Purple Loosestrife (Lythrum salicaria). Weed Technology, vol. 12:397-401; personal observation; ancedotal


Question 2.7 Other regions invaded? A Reviewed Scientific Publication
Identify other regions:

see rationale purple loosestrife invades marshes, bogs, seeps, and reservoirs in many eastern and lakes states; purple loosestrife has yet to exploit these habitats in California; the range of purple loosestrife in the U.S. has greatly expanded since 1941, colonization of northern midwest in nearly complete; the most dramatic expansion, however, has been in the arid West, including staes of California, Idaho, Washington, Montana, and Wyoming.


Sources of information:

Thompson, D.Q., R.L. Stuckey, and E.B. Thompson, 1987. Spread, impact, and control of purple loosestrife in North American Wetlands. Fish and Wildlife No. 2 U.S. Dept. Interior, Fish and Wildlife Service, Washington, D.C. 55pp.; Missouri Vegetation Management Manual, Tim Smith, Natural History Division;

California Department of Food and Agriculture Purple Loosestrife Program documents, reports, grant proposals, and mapping documentation; personal observation; ancedotal


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? A Other Published Material

see rationale In a limited manner, purple loosestrife has invaded the following ecological types in California: lakes (Shasta and Butte counties), ponds (Nevada and Placer counties), rivers/steams (Delta, Fresno County), canals (Shasta and San Joaquin counties), meadows (sections along Delta, Kern County, etc.)
Statewide in California, purple loosestrife has not reached near it's suspected capacity in total available habitat types (freshwater, estuarine: lakes, ponds, reservoirs, rivers, streams, canals); To a much lesser extent: meadows; marsh, riparian forest, woodland, and not yet in limited bog/seep types (while not as prevalent in California as back East and in Lake states).


Sources of information:

California Department of Food and Agriculture Purple Loosestrife Program documents, reports, grant proposals, and mapping documentation; personal observation; ancedotal


Question 3.2 Distribution/Peak frequency? D Other Published Material
Describe distribution:

see rationale Statewide in California, purple loosestrife has not reached near it's suspected capacity in total available habitat types (freshwater, estuarine: lakes, ponds, reservoirs, rivers, streams, canals); To a much lesser extent: meadows; marsh, riparian forest, woodland, and not yet in limited bog/seep types (while not as prevalent in California as back East and in Lake states).
Statewide, purple loostrife has invaded very little of it's potential range; In a limited manner, purple loosestrife has invaded the following ecological types in California: lakes (shasta and butte counties), ponds (Nevada and placer counties), rivers/steams (Delta, Fresno counties), canals (shasta and san joaquin counties), meadows (sections along Delta, Kern county, etc.)


Sources of information:

California Department of Food and Agriculture Purple Loosestrife Program documents, reports, grant proposals, and mapping documentation; personal observation; ancedotal


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter Yes
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually Yes
Seeds remain viable in soil for three or more years Yes
Viable seed produced with both self-pollination and cross-pollination No
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere Yes
Resprouts readily when cut, grazed, or burned Yes
Total points: 10
Total unknowns: 0
Total score: A?

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirsD, < 5%
Aquatic Systemsrivers, streams, canalsD, < 5%
estuariesD, < 5%
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seepD, < 5%
alkali playa
pebble plain
Bog and Marshbog and fenD, < 5%
marsh and swampD, < 5%
Riparian and Bottomland habitatriparian forestD, < 5%
riparian woodlandD, < 5%
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): A
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Cascade Range
  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest
  • Modoc Plateau
  • Mojave Desert