Source: California Invasive Plant Council


URL of this page: http://www.cal-ipc.org/site/paf/509
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Cal-IPC Plant Assessment Form

For use with "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands"
by the California Invasive Plant Council and the Southwest Vegetation Management Association

Table 1. Species and Evaluator Information

Species name
(Latin binomial):
The official Latin binomial name for this species. Specify only one name here. Additional species names may go into the Synonyms field.

Lepidium latifolium

Synonyms:
Additional Latin binomial names for this species. Separate multiple names with a ; character. Please avoid narrative descriptions, and list only the binomial names.
Cardaria latifolia (L.) Spach
Common names:
Common names for this species. Separate multiple names with a ; character.
perennial pepperweed; tall whitetop; broadleaved pepperweed
Evaluation date:
The date(s) when this species PAF was filled out, modified, or reviewed. This is free-form text, so it may include multiple dates or other notes.
05/08/03
Evaluator #1 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
Evaluator #2 Joe DiTomaso
UC Davis
Weed Science Program, Robbins Hall, Univ. California, Davis CA 95616
530-754-8715
DiTomaso@vegmail.ucdavis.edu
List committee members: Carla Bossard, Joe DiTomaso, John Randall, Cynthia Roye, Jake Sigg, Alison Stanton, Peter Warner
Committee review date: 03/19/04
List date:
Re-evaluation date(s):
General comments
on this assessment:
Enter any additional notes about this assessment, such as factors affecting the reliability or completeness of the answers, likely affects of impacts, or research which is not specific to California but is still relevant in the evaluation of this species.

Table 2. Criteria, Section, and Overall Scores

Overall Score

Plant scoring matrix
Based on letter scores from Sections 1 through 3 below

ImpactInvasivenessDistribution
AA BAnyHighNo Alert
AC DAnyModerateAlert
BA BA BModerateNo Alert
BA BC DModerateAlert
BC DAnyLimitedNo Alert
CAA BModerateNo Alert
CAC DLimitedNo Alert
CBAModerateNo Alert
CBB DLimitedNo Alert
CCAnyLimitedNo Alert
DAnyAnyNot ListedNo Alert

High

Alert Status

Plant scoring matrix
Based on letter scores from Sections 1 through 3 below

ImpactInvasivenessDistributionAlert
AA or BC or DAlert
BA or BC or DAlert

No Alert

Documentation

The total documentation score is the average
of Documentation scores given in Table 2.

Reviewed Scientific Publication4 points
Other Published Material3 points
Observational2 points
Anecdotal1 points
Unknown or No Information0 points

3.1 out of 5

Score Documentation
1.1 Impact on abiotic ecosystem processes
Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include:
- fire occurrence, frequency, and intensity;
- geomorphological changes such as erosion and sedimentation rates;
- hydrological regimes, including soil water table;
- nutrient and mineral dynamics, including salinity, alkalinity, and pH;
- light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open).

Select the one letter below that best describes this species’ most severe impact on an abiotic ecosystem process:
A. Severe, possibly irreversible, alteration or disruption of an ecosystem process.
B. Moderate alteration of an ecosystem process.
C. Minor alteration of an ecosystem process.
D. Negligible perceived impact on an ecosystem process.
U. Unknown.
A. Severe Reviewed Scientific Publication
Impact
Section 1 Scoring Matrix
Q 1.1Q 1.2Q 1.3Q 1.4Score
AAAnyAnyA
ABA,BAnyA
ABC,D,UAnyB
AC,D,UAnyAnyB
BAAAnyA
BABAA
BAB,CB-D,UB
BAC,D,UAA
BAC,D,UB-D,UB
BBAAA
BC,D,UAAB
BB-DAB-D,UB
BB-DB-D,UAnyB
BD,UC,D,UA-BB
BD,UC,D,UC,D,UC
C-D,UAAAnyA
CBAAnyB
CA,BB-D,UAnyB
CC,D,UAnyAnyC
DA,BBAnyB
DA,BC,D,UAnyC
DCAnyAnyC
DD,UAnyAnyD
UAB,CAnyB
UB,CA,BAnyB
UB,CC,D,UAnyC
UUAnyAnyU


Four-part score
AABU

Total Score
A
1.2 Impact on plant community
Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include:
- formation of stands dominated (>75% cover) by the species;
- occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below;
- significant reduction or extirpation of populations of one or more native species.

Examples of impacts usually less than severe include:
- reduction in propagule dispersal, seedling recruitment, or survivorship of native species;
- creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer;
- change in density or depth of a structural layer;
- change in horizontal distribution patterns or fragmentation of a native community;
- creation of a vector or intermediate host of pests or pathogens that infect native plant species.

Select the one letter below that best describes this species’ impact on community composition, structure and interactions:
A. Severe alteration of plant community composition, structure, or interactions.
B. Moderate alteration of plant community composition.
C. Minor alteration of community composition.
D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions.
U. Unknown.
A. Severe Reviewed Scientific Publication
1.3 Impact on higher trophic levels
Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species’ net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types.
Examples of severe impacts include:
- extirpation or endangerment of an existing native species or population;
- elimination or significant reduction in native species’ nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors.

Examples of impacts that are usually less than severe include:
- minor reduction in nesting or foraging sites, cover, etc. for native animals;
- minor reduction in habitat connectivity or migratory corridors;
- interference with native pollinators;
- injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species.

Select the one letter below that best describes this species’ impact on community composition and interactions:
A. Severe alteration of higher trophic populations, communities, or interactions.
B. Moderate alteration of higher trophic level populations, communities, or interactions.
C. Minor alteration of higher trophic level populations, communities or interactions.
D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions.
E. Unknown.
B. Moderate Other Published Material
1.4 Impact on genetic integrity
Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include:
- production of fertile or sterile hybrids that can outcompete the native species;
- production of sterile hybrids that lower the reproductive output of the native species.

Select the one letter below that best describes this species’ impact on genetic integrity:
A. Severe (high proportion of individuals).
B. Moderate (medium proportion of individuals).
C. Minor (low proportion of individuals).
D. No known hybridization.
U. Unknown.
U. Unknown Other Published Material
2.1 Role of anthropogenic and natural disturbance in establishment
Assess this species’ dependence on disturbance—both human and natural—for establishment in wildlands. Examples of anthropogenic disturbances include:
- grazing, browsing, and rooting by domestic livestock and feral animals;
- altered fire regimes, including fire suppression;
- cultivation;
- silvicultural practices;
- altered hydrology due to dams, diversions, irrigation, etc.;
- roads and trails;
- construction;
- nutrient loading from fertilizers, runoff, etc.

Examples of natural disturbance include:
- wildfire;
- floods;
- landslides;
- windthrow;
- native animal activities such as burrowing, grazing, or browsing.

Select the first letter in the sequence below that describes the ability of this species to invade wildlands:
A. Severe invasive potential—this species can establish independent of any known natural or anthropogenic disturbance.
B. Moderate invasive potential—this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances.
C. Low invasive potential—this species requires anthropogenic disturbance to establish.
D. No perceptible invasive potential—this species does not establish in wildlands (though it may persist from former cultivation).
U. Unknown.
A. Severe Other Published Material
Invasiveness
Section 2 Scoring Matrix
Total pointsScore
17-21A
11-16B
5-10C
0-4D
More than two U’sU


Total Points
18

Total Score
A
2.2 Local rate of spread with no management
Assess this species’ rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented.

Select the one letter below that best describes the rate of spread:
A. Increases rapidly (doubling in <10 years)
B. Increases, but less rapidly
C. Stable
D. Declining
U. Unknown
A. Increases rapidly Other Published Material
2.3 Recent trend in total area infested within state
Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them.

Select the one letter below that best describes the current trend:
A. Increasing rapidly (doubling in total range statewide in <10 years)
B. Increasing, but less rapidly
C. Stable
D. Declining
U. Unknown
A. Increasing rapidly Other Published Material
2.4 Innate reproductive potential
(see Worksheet A)
Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.
A. High Other Published Material
2.5 Potential for human-caused dispersal
Assess whether this species is currently spread—or has high potential to be spread—by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include:
- commercial sales for use in agriculture, ornamental horticulture, or aquariums;
- use as forage, erosion control, or revegetation;
- presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.;
- spread along transportation corridors such as highways, railroads, trails, or canals;
- transport on boats or boat trailers.

Select the one letter below that best describes human-caused dispersal and spread:
A. High—there are numerous opportunities for dispersal to new areas.
B. Moderate—human dispersal occurs, but not at a high level.
C. Low—human dispersal is infrequent or inefficient.
D. Does not occur.
U. Unknown.
B. Moderate Other Published Material
2.6 Potential for natural long-distance dispersal
We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms:
- the species’ fruit or seed is commonly consumed by birds or other animals that travel long distances;
- the species’ fruits or seeds are sticky or burred and cling to feathers or hair of animals;
- the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water;
- the species has light propagules that promote long-distance wind dispersal;
- The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed).

Select the one letter below that best describes natural long-distance dispersal and spread:
A. Frequent long-distance dispersal by animals or abiotic mechanisms.
B. Occasional long-distance dispersal by animals or abiotic mechanisms.
C. Rare dispersal more than 1 km by animals or abiotic mechanisms.
D. No dispersal of more than 1 km by animals or abiotic mechanisms.
U. Unknown.
A. Frequent Other Published Material
2.7 Other regions invaded
Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state.

Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range.
A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively).
B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state.
C. Invades elsewhere but only in ecological types that it has already invaded in the state.
D. Not known as an escape anywhere else.
U. Unknown.
C. Already invaded Other Published Material
3.1 Ecological amplitude/Range
(see Worksheet C)
Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades.
A. Widespread—the species invades at least three major types or at least six minor types.
B. Moderate—the species invades two major types or five minor types.
C. Limited—the species invades only one major type and two to four minor types.
D. Narrow—the species invades only one minor type.
U. Unknown.
A. Widespread Other Published Material
Distribution
Section 3 Scoring Matrix
Q 3.1Q 3.2Score
AA, BA
AC,D,UB
BAA
BB,CB
BDC
CA,BB
CC,DC
DAB
DB,CC
DDD
A,BUC
C,DUD
UUU


Total Score
A
3.2 Distribution/Peak frequency
(see Worksheet C)
To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.
B. Moderate Observational

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".
Short citations may be used in this table. List full citations at end of this table.

Section 1: Impact

Reviewed Scientific Publication A Question 1.1 Impact on abiotic ecosystem processes
Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include:
- fire occurrence, frequency, and intensity;
- geomorphological changes such as erosion and sedimentation rates;
- hydrological regimes, including soil water table;
- nutrient and mineral dynamics, including salinity, alkalinity, and pH;
- light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open).

Select the one letter below that best describes this species’ most severe impact on an abiotic ecosystem process:
A. Severe, possibly irreversible, alteration or disruption of an ecosystem process.
B. Moderate alteration of an ecosystem process.
C. Minor alteration of an ecosystem process.
D. Negligible perceived impact on an ecosystem process.
U. Unknown.
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.

Reviewed Scientific Publication A Question 1.2 Impact on plant community composition,
structure, and interactions
Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include:
- formation of stands dominated (>75% cover) by the species;
- occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below;
- significant reduction or extirpation of populations of one or more native species.

Examples of impacts usually less than severe include:
- reduction in propagule dispersal, seedling recruitment, or survivorship of native species;
- creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer;
- change in density or depth of a structural layer;
- change in horizontal distribution patterns or fragmentation of a native community;
- creation of a vector or intermediate host of pests or pathogens that infect native plant species.

Select the one letter below that best describes this species’ impact on community composition, structure and interactions:
A. Severe alteration of plant community composition, structure, or interactions.
B. Moderate alteration of plant community composition.
C. Minor alteration of community composition.
D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions.
U. Unknown.
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.

Other Published Material B Question 1.3 Impact on higher trophic levels
Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species’ net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types.
Examples of severe impacts include:
- extirpation or endangerment of an existing native species or population;
- elimination or significant reduction in native species’ nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors.

Examples of impacts that are usually less than severe include:
- minor reduction in nesting or foraging sites, cover, etc. for native animals;
- minor reduction in habitat connectivity or migratory corridors;
- interference with native pollinators;
- injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species.

Select the one letter below that best describes this species’ impact on community composition and interactions:
A. Severe alteration of higher trophic populations, communities, or interactions.
B. Moderate alteration of higher trophic level populations, communities, or interactions.
C. Minor alteration of higher trophic level populations, communities or interactions.
D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions.
E. Unknown.
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.

Other Published Material U Question 1.4 Impact on genetic integrity
Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include:
- production of fertile or sterile hybrids that can outcompete the native species;
- production of sterile hybrids that lower the reproductive output of the native species.

Select the one letter below that best describes this species’ impact on genetic integrity:
A. Severe (high proportion of individuals).
B. Moderate (medium proportion of individuals).
C. Minor (low proportion of individuals).
D. No known hybridization.
U. Unknown.
Identify impacts:
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

Other Published Material A Question 2.1 Role of anthropogenic and natural disturbance
in establishment
Assess this species’ dependence on disturbance—both human and natural—for establishment in wildlands. Examples of anthropogenic disturbances include:
- grazing, browsing, and rooting by domestic livestock and feral animals;
- altered fire regimes, including fire suppression;
- cultivation;
- silvicultural practices;
- altered hydrology due to dams, diversions, irrigation, etc.;
- roads and trails;
- construction;
- nutrient loading from fertilizers, runoff, etc.

Examples of natural disturbance include:
- wildfire;
- floods;
- landslides;
- windthrow;
- native animal activities such as burrowing, grazing, or browsing.

Select the first letter in the sequence below that describes the ability of this species to invade wildlands:
A. Severe invasive potential—this species can establish independent of any known natural or anthropogenic disturbance.
B. Moderate invasive potential—this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances.
C. Low invasive potential—this species requires anthropogenic disturbance to establish.
D. No perceptible invasive potential—this species does not establish in wildlands (though it may persist from former cultivation).
U. Unknown.
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.

Other Published Material A Question 2.2 Local rate of spread with no management
Assess this species’ rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented.

Select the one letter below that best describes the rate of spread:
A. Increases rapidly (doubling in <10 years)
B. Increases, but less rapidly
C. Stable
D. Declining
U. Unknown
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.

Other Published Material A Question 2.3 Recent trend in total area infested within state
Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them.

Select the one letter below that best describes the current trend:
A. Increasing rapidly (doubling in total range statewide in <10 years)
B. Increasing, but less rapidly
C. Stable
D. Declining
U. Unknown
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.

Other Published Material A Question 2.4 Innate reproductive potential
Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.
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.

Other Published Material B Question 2.5 Potential for human-caused dispersal
Assess whether this species is currently spread—or has high potential to be spread—by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include:
- commercial sales for use in agriculture, ornamental horticulture, or aquariums;
- use as forage, erosion control, or revegetation;
- presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.;
- spread along transportation corridors such as highways, railroads, trails, or canals;
- transport on boats or boat trailers.

Select the one letter below that best describes human-caused dispersal and spread:
A. High—there are numerous opportunities for dispersal to new areas.
B. Moderate—human dispersal occurs, but not at a high level.
C. Low—human dispersal is infrequent or inefficient.
D. Does not occur.
U. Unknown.
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

Other Published Material A Question 2.6 Potential for natural long-distance dispersal
We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms:
- the species’ fruit or seed is commonly consumed by birds or other animals that travel long distances;
- the species’ fruits or seeds are sticky or burred and cling to feathers or hair of animals;
- the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water;
- the species has light propagules that promote long-distance wind dispersal;
- The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed).

Select the one letter below that best describes natural long-distance dispersal and spread:
A. Frequent long-distance dispersal by animals or abiotic mechanisms.
B. Occasional long-distance dispersal by animals or abiotic mechanisms.
C. Rare dispersal more than 1 km by animals or abiotic mechanisms.
D. No dispersal of more than 1 km by animals or abiotic mechanisms.
U. Unknown.
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.

Other Published Material C Question 2.7 Other regions invaded
Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state.

Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range.
A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively).
B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state.
C. Invades elsewhere but only in ecological types that it has already invaded in the state.
D. Not known as an escape anywhere else.
U. Unknown.
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

Other Published Material A Question 3.1 Ecological amplitude/Range
Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades.
A. Widespread—the species invades at least three major types or at least six minor types.
B. Moderate—the species invades two major types or five minor types.
C. Limited—the species invades only one major type and two to four minor types.
D. Narrow—the species invades only one minor type.
U. Unknown.
Describe ecological amplitude, identifying date of source information and approximate date of introduction to the state, if known:
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.

Observational B Question 3.2 Distribution/Peak frequency
To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.
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, 1 points
Dense infestations produce >1,000 viable seed per square meter Yes, 2 points
Populations of this species produce seeds every year. Yes, 1 points
Seed production sustained over 3 or more months within a population annually Yes, 1 points
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination Yes, 1 points
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes, 1 points
Fragments easily and fragments can become established elsewhere Yes, 2 points
Resprouts readily when cut, grazed, or burned Yes, 1 points
Total points: 10
Total unknowns: 0
Total score: A
Scoring Criteria for Worksheet A
A. High reproductive potential (6 or more points).
B. Moderate reproductive potential (4-5 points).
C. Low reproductive potential (3 points or less and less than 3 Unknowns).
U. Unknown (3 or fewer points and 3 or more Unknowns).
Note any related traits:
most seed germinates on first year.
Return to Table 2

Worksheet B - Arizona Ecological Types is not included here


Worksheet C - California Ecological Types
 
(sensu Holland 1986)

Major Ecological Types Minor Ecological Types Code
A means >50% of type occurrences are invaded;
B means >20% to 50%;
C means >5% to 20%;
D means present but ≤5%;
U means unknown (unable to estimate percentage of occurrences invaded)
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, coastal prairieC. 5% - 20%
Meadows, and other Herbvalley and foothill grasslandC. 5% - 20%
CommunitiesGreat 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)  
Distribution (highest score)  
Return to Table 2

Addendum J - Jepson Regions Infested
 
Click here for a map of Jepson regions

Infested Jepson Regions:
Check the boxes to indicate the Jepson floristic provinces in which this species is found.














Addendum L - External Links & Resources

Cal-IPC Plant Profile
The Cal-IPC Plant Profile for this species.
http://www.cal-ipc.org/ip/management/plant_profiles/Lepidium_latifolium.php
Calflora Plant Profile:
The Calflora Plant Profile for this species.
http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=4691
CalWeedMapper:
Load CalWeedMapper with this species already selected.
http://calweedmapper.cal-ipc.org/maps/?species=82