Plant Assessment Form

Lepidium latifolium

Synonyms: Cardaria latifolia (L.) Spach

Common Names: perennial pepperweed; tall whitetop; broadleaved pepperweed

Evaluated on: 5/8/03

List committee review date: 19/03/2004

Re-evaluation date:

Evaluator(s)

Cynthia L. Roye/ Associate State Park Resource Ecologist
California State Parks, Natural Resources Division
P.O. Box 942896, Sacramento, CA 94296-0001
(916) 653-9083
croye@parks.ca.gov
Joe DiTomaso
UC Davis
Weed Science Program, Robbins Hall, Univ. California, Davis CA 95616
530-754-8715
DiTomaso@vegmail.ucdavis.edu

List commitee members

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

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

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

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:

A. Alters soil salinity. May act as "salt pump" as it removes salts from deep in the soil profile and deposits them on soil surface. Builds a dense organic layer in soil surface that alters carbon/nitrogen ratio. May allow compact soil to become more friable after 5 to 10 years by plant-cycled nitrogen (Blank and Young, 1999, abstract as accessed on the Internet at:http:www.nal.usda.gov/ttic/tektran/data/000009/95/0000099552.html) Adapted to using water with high salt content, but not obligate. May act as "salt pump" as it removes salts from deep in the soil profile and deposits them on soil surface.


Sources of information:

Blank and Young, 1997, as cited by Renz, M.J. 2000. TNC Element Stewardship Abstract as accessed over the Internet at:http://tncweeds.ucdavis.edu/esadocs/documnts/lepilat.pdf; Written findings of the State (WA) Noxious Weed Control Board as accessed over the Internet at:http://www.nwcb.wa.gov/weed_info/pepperweed.html; Young et al. 1995. Ecology and Control of Perennial Pepperweed (Lepidium latifolium). CalEPPC 1995 Symposium Proceedings. 4 pg.; Howald A. IN: Bossard et al. 2000. Invasive plants of California's wildlands. California Exotic Pest Plant Council. UC Press, Berkeley, pp. 222-224.


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

A. Forms dense monospecific stands that exclude other plants, including natives. By altering salinity, favors halophytes overothers and shifts plant composition and diversity. Old stems take several years to degrade and can form a layer impenetrable to light. Annual plants may be unable to emerge. Encroaching on populations of several rare salt marsh plants including Cordylanthus mollis ssp. mollis, Circium hydrophilum var. hydrophilum, and Aster lentus. Forms dense monospecific stands that exclude other plants, including natives. By altering salinity, favors halophytes overothers and shifts plant composition and diversity. Old stems take several years to degrade and can form a layer impenetrable to light. Annual plants may be unable to emerge. Encroaching on populations of several rare salt marsh plants including Cordylanthus mollis ssp. mollis, Circium hydrophilum var. hydrophilum, and Aster lentus.


Sources of information:

Renz, M. J. 2000. TNC Element Stewardship Abstract for Lepidium latifolium as accessed over the Internet at:http://tncweeds.ucdavis.edu/esadocs/documnts/lepilat.pdf; Howald, A. IN: Bossard et al. 2000.


Question 1.3 Impact on higher trophic levels? B Other Published Material
Identify type of impact or alteration:

B. Poses threat to the habitat of endangered salt marsh harvest mouse, California clapper rail, California black rail. Lessens food availability for nesting waterfowl. Prefers habitat higher than that where pickleweed grows but has invaded Salifornia-dominated marshes in Alviso Slough. Outcompetes grasses that provide food for waterfowl.


Sources of information:

Howald, A. IN: Bossard et al. 2000.


Question 1.4 Impact on genetic integrity? U Other Published Material

U. Has fifteen closely related California natives and four related non-natives. Unknown if genetic contamination occurs.


Sources of information:

Howald, A. IN: Bossard et al. 2000.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
A Other Published Material
Describe role of disturbance:

B. Most frequently found in areas with some natural or anthropogenic disturbance such as riparian areas, marshes, estuaries, irrigation channels, wetlands and floodplains. If introduced, can proliferate in roadsides, native hay meadows (unplowed), alfalfa fields, and rangelands. most of the areas where this plant occurs are subject to some form of disturbance.


Sources of information:

Howald, A. IN: Bossard et al. 2000; Renz, M.J. 2002. Biology, Ecology, and Control of Perennial Pepperweed (Lepidium latifolium). Ph. D. Dissertation in Plant Biology, University of California, Davis. 128 p. as accessed on the Internet at:http://wric.ucdavis.edu/information/pepperweed-renz.pdf.


Question 2.2 Local rate of spread with no management? A Other Published Material
Describe rate of spread:

A. Expansion of populations occurs primarily at the leading edge of the infestation, rarely more than 2 m from previious infestation. Althouogh the plants can produce many seeds annually, seedlings are rarely found in the field, populations spread clonally, per Renz. Without treatment, the spread at Renz' three sites was measured at 44% to 129% over a two year period. At this rate doubling would occur in fewer than ten years. Undisturbed populations spread clonally along the leading edge of the infestation. Density of the stems also increases over time making control of the infestation and re-establishment of native plants more difficult.


Sources of information:

Renz, M.J. 2002. Biology, Ecology, and Control of Perennial Pepperweed (Lepidium latifolium). Ph. D. Dissertation in Plant Biology, University of California, Davis. 128 p., as accessed on the Internet at:http://wric.ucdavis.edu/information/pepperweed-renz.pdf.


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

A. The first record of this plant in California is from a ranch north of Oakdale in 1936. The plant is now found in most California counties. Distribution map as shown in species treatment in Bossard et al. 2000.


Sources of information:

Howald, A. IN: Bossard et el. 2000.


Question 2.4 Innate reproductive potential? A Other Published Material
Describe key reproductive characteristics:

A. seeds, rhizomes, fragments Prolific seeder producing up to 6 billion seeds per acre; seeds transported by wind, water, and waterfolw but have no mechanisms for long-distance dispersal; also produces rhizomes that can fragment and sprout.


Sources of information:

Howald, A. IN: Bossard et al. 2000; Keuger and Sheley. 1996. MT9906 Agriculture, Perennial Pepperweed as accessed on the Internet at: http://www.montana.edu/wwwpb/pubs/mt9906.html. Renz, M.J. 2002. Biology, Ecology, and Control of Perennial Pepperweed (Lepidium latifolium). Ph. D. Dissertation in Plant Biology, University of California, Davis. 128 p., as accessed on the Internet at:http://wric.ucdavis.edu/information/pepperweed-renz.pdf.


Question 2.5 Potential for human-caused dispersal? B Other Published Material
Identify dispersal mechanisms:

B. Collected for dried flower arrangements; seed or plant fragments may be a contaminant of rice straw bales used in erosion control, may be moved on agricultural equipment, or by waterfowl. Collected for dried flower arrangements, seed or plant fragments may be a contaminant of rice straw bales used in erosion control or may be moved on agricultural equipment.


Sources of information:

Howald, A. IN: Bossard et al. 2000; Washington State Noxious Weed Control Board as accessed on the Internet at:http://www.nwcb.wa.gov/weed_info/pepperweedwf.html


Question 2.6 Potential for natural long-distance dispersal? A Other Published Material
Identify dispersal mechanisms:

Seeds have no special mechanisms for long-range dispersal. Can be transported by wind, water and, possibly, waterfowl. Seeds have no special mechanisms for long-range dispersal. Can be spreadf by pieces od undergrounf stems.


Sources of information:

Howald, A. IN: Bossard et al. 2000.


Question 2.7 Other regions invaded? C Other Published Material
Identify other regions:

C. Native range Mediterranean Basin to temperate Europe and east to Middle East, Asia, and Himilayas. Introduced New England to Mexico and occurs in all far-western states. Appears to occupy similar habitats to those occupied in California. Introduced New England to Mexico and occurs in all far-western states. Appears to occupy similar habitats to those occupied in California.


Sources of information:

Washington State Noxious Weed Control Board as accessed on the Internet at:http://www.nwcb.wa.gov/weed_info/pepperweedwf.html.


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

A. The first record of this plant in California is from a ranch north of Oakdale in 1936. The plant is now found in most California counties. It is found in riparian areas, marshes, estuaries, irrigtion channels, wetlands, and floodplains but may also occur on roadsides, native hay meadows, alfalfa fields, and rangelands. This plant occurs in 12 California State Park units from Bidwell SacramentoRiver SP in the Great Central Valley to San Pasqual Battlefirld SHP east of Escondido. It was listed among the Top Ten Most Unwanted Weeds in 24 California Counties according to a poll taken by the California Department of Food and Agriculture published in the Noxious Times as accessed on the Internet at: http://www.cdfa.ca.gov/phpps/ipc/noxioustimes/pdfs/2003spring.pdf.


Sources of information:

Howald, A. IN: Bossard et al. 2000; California State Parks 2002 Natural Resources Condition Assessment, Natural Resources Division, Sacramento, CA; Noxious Times as on the Internet at: http://www.cdfa.ca.gov/phpps/ipc/noxioustimes/pdfs/2003spring.pdf.
Young et al. 1995. Ecology and Control of Perennial Pepperweed (Lepidium latifolium). CalEPPC 1995 Symposium Proceedings. 4 pg.


Question 3.2 Distribution/Peak frequency? B Observational
Describe distribution:

B. Consensus of Committee member observations as expressed 2/10/03 and 3/19/04 meeting s in Davis.


Sources of information:

Observations of Weed Ranking Committee members. I lack published sources to document these observations.


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 No
Viable seed produced with both self-pollination and cross-pollination Yes
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
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:

most seed germinates on first year.

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, reservoirs
Aquatic Systemsrivers, streams, canals
estuaries
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 prairieC, 5% - 20%
valley and foothill grasslandC, 5% - 20%
Great Basin grasslandD, < 5%
vernal poolC, 5% - 20%
meadow and seepU, Unknown
alkali playa
pebble plain
Bog and Marshbog and fenB, 20% - 50%
marsh and swampC, 5% - 20%
Riparian and Bottomland habitatriparian forestC, 5% - 20%
riparian woodlandC, 5% - 20%
riparian scrub (incl.desert washes)D, < 5%
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): B

Infested Jepson Regions

Click here for a map of Jepson regions

  • CA Floristic Province
  • Cascade Range
  • Central West
  • Desert Province
  • Mojave Desert
  • Sonoran Desert
  • Great Basin Province
  • Great Valley
  • Modoc Plateau
  • Northwest
  • Sierra Nevada
  • Sierra Nevada East
  • Southwest