Plant Assessment Form

Lepidium chalepense

Synonyms: Cardaria chalepensis, Cardaria draba ssp. chalepensis, Cardaria draba ssp. repens, C. draba ver. repens, Lepidium draba var. repens, Lepidium repens

Common Names: lens-podded hoary cress, lens-podded whitetop, hoary cress, peppergrass; whitetop, whiteweed, cranson rampant, chalapa whitetop

Evaluated on: 8/6/04

List committee review date: 27/08/2004

Re-evaluation date:

Evaluator(s)

Brianna Richardson, Project Manager
California Invasive Plant Council
1442-A Walnut Street #462, Berkeley, CA 94709
510.843.3902
brichardson@cal-ipc.org
Joseph M. DiTomaso/ Cooperative Ext. Specialist
University of California
Weed Science Program, Robbins Hall, Davis, CA 95616
530-754-8715
ditomaso@vegmail.ucdavis.edu

List commitee members

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

General Comments

Removed second scientific name, Cardaria chalepensis, and added it to the synonym line 3/28/17. Ramona Robison

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? Alert
Documentation? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Other Published Material
Impact?
Four-part score CBCD Total Score
B
1.2 ?Impact on plant community B. Moderate Other Published Material
1.3 ?Impact on higher trophic levels C. Minor Other Published Material
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Other Published Material
Invasiveness?
Total Points
12 Total Score B
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 C. Stable Other Published Material
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal C. Low Other Published Material
2.6 ? Potential for natural long-distance dispersal C. Rare Other Published Material
2.7 ?Other regions invaded C. Already invaded Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Other Published Material
Distribution?
Total Score C
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? C Other Published Material
Identify ecosystem processes impacted:

Reduces available soil moisture and nutrients early in the season. In Australia, slowed water drainage and increased flooding. Cardaria draba is known to salinify the soil, but no evidence indicates that C. chalepensis does the same. Has the potential to impact abiotic systems, unclear whether this occurs in CA.


Sources of information:

Kadrmas, T., WS Johnson. UNR Cooperative Extension Fact Sheet FS-02-56: Managing hoary cress. Accessed 8/2004 www.unce.unr.edu.
Bossard, CC. JM Randall, MC Hoshovsky. 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley: 81-86.


Question 1.2 Impact on plant community composition,
structure, and interactions?
B Other Published Material
Identify type of impact or alteration:

Threatens several rare plants in ID. Dense stands of perennial grasses are somewhat immune from invasion in the PNW. Considered by TNC to be a moderate threat to habitat and other plant species. "Reduces native biodiversity and forage quality." Can form dense monocultures, displacing native plants. Populations in California are not common. Though said to reduce native biodiversity, this plant is considered easy to control. It is not competitive against shrubs. May not be competitive against established perennial grasses. Needs high moisture or irrigation to become established and thrive. May be a problem along waterways or in high rainfall areas. Primarily an agricultural pest. May form monocultures under ideal conditions. Can cause moderate (sometimes severe) alteration of plant community composition.


Sources of information:

Hill, Janice. 1999. Weed Report: Cardaria draba ssp. chalepensis. TNC Wildand Weed Survey.
Miller, TW. 1991. Hoary cress and related whitetops. PNW Weeds 359.
Lyons, KE. 2000. Element Stewardship Abstract: Cardaria draba, C. chalepensis, C. pubescens. The Nature Conservancy Wildland Invasive Speices Team.
Anonymous. Montana omes and Land website: Noxious Weeds: hoary cress (C. chalepensis). Accessed 8/2004.
Kadrmas, T., WS Johnson. UNR Cooperative Extension Fact Sheet FS-02-56: Managing hoary cress. Accessed 8/2004 www.unce.unr.edu.


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

Flowers often visited by insects. "Reduces native biodiversity and forage quality." Reduces available forage for livestock. Toxic to cattle. Provide nectar for honeybees. Unclear whether C.chalepensis significantly reduces forage (or poses a poisoning threat to) wildlife in California.


Sources of information:

Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
Lyons, KE. 2000. Element Stewardship Abstract: Cardaria draba, C. chalepensis, C. pubescens. The Nature Conservancy Wildland Invasive Speices Team.
Anonymous. Montana omes and Land website: Noxious Weeds: hoary cress (C. chalepensis). Accessed 8/2004.
Kadrmas, T., WS Johnson. UNR Cooperative Extension Fact Sheet FS-02-56: Managing hoary cress. Accessed 8/2004 www.unce.unr.edu.


Question 1.4 Impact on genetic integrity? D Other Published Material

No native members of the genus in California. All Cardaria spp in CA are introduced.


Sources of information:

CalFlora database. www.calflora.org. Accessed 8/2004


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

Establishes more readily on irrigated land. Heavy grazing may encourage establishment. Invasion potential is greater under conditions of disturbance. Literature indicates that disturbance increases establishment, but is not necessary under all conditions.


Sources of information:

Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
Lyons, KE. 2000. Element Stewardship Abstract: Cardaria draba, C. chalepensis, C. pubescens. The Nature Conservancy Wildland Invasive Speices Team.
CDFA Encycloweedia: www.cdfa.ca.gov Accessed 8/2004.


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

In Saskatchewan, C. chalepensis often spreads more than 2 ft in diameter/year under favorable conditions (moisture present, no shrubs). In sites dominated by shrubs, however, it receded in size. In MT, a single plant can grow to cover 12 ft in diameter in its first year, growing 2-5 ft in diameter in subsequent years. Under favorable conditions (likely present if establishment occurs) the plant can spread very quickly.


Sources of information:

Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
Anonymous. Montana omes and Land website: Noxious Weeds: hoary cress (C. chalepensis). Accessed 8/2004.


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

Since the plant is on the state noxious weed list, it is often controlled. Populations are not common in the state and it does not appear to be spreading, perhaps do to the management efforts. It may even be declining.


Sources of information:

California Dept. of Food and Agriculture. Encycloweedia. Accessed 8/2004. www.cdfa.ca.gov.


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

Vigorously creeping horizontal roots can create clonal colonies. Under favorable conditions, plants can increase vegetatively by more than 61 cm radius/year. Self-incompatible. Root fragments can generate new plants. Flowers April-August. Plants do not flower the first year. One flowering stem can produce up to 850 mature pods. Will regenerate from roots after mowing (and probably grazing). Has a higher ability to recover from injury than C. draba. 52% of seeds can remain viable after 3 years. Under favorable conditions, seeds produced every year after the first. Under unfavorable (dry) conditions seeds are sometimes not produced. Under favorable conditions, a single stem can produce 1000-5000 seeds. 11 points.


Sources of information:

DiTomaso, J, E. Healy. Weeds of California and Other Western States. Not yet published.
Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
Bossard, CC. JM Randall, MC Hoshovsky. 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley: 81-86.


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

Cultivation can enhance dispersal by moving root fragments. Seeds and root fragments can be spread by vehicles and machinery, and seeds can be moved in hay and crop seed. Movement to wildland areas however, is probably uncommon. Potential exists for dispersal as a contaminant. Commonly spread by human activites. Illegal to import products contaminated with C. chalepensis into CA. (May be spread within CA.)


Sources of information:

DiTomaso, J, E. Healy. Weeds of California and Other Western States. Not yet published.
Anonymous. Montana omes and Land website: Noxious Weeds: hoary cress (C. chalepensis). Accessed 8/2004.
CDFA. Encycloweedia. www.cdfa.ca.gov. Accessed 8/2004.
Bossard, CC. JM Randall, MC Hoshovsky. 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley: 81-86.


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

Seeds can be spread by wind and on waterways. Seeds remain viable for only 1 month in manure. Root fragments carried by streams. Most seed probably fall directly to the soil beneath the parent plant and very few seeds are transported long distances. At least occasionally spread by animal and abiotic action.


Sources of information:

Anonymous. Montana omes and Land website: Noxious Weeds: hoary cress (C. chalepensis). Accessed 8/2004.
CDFA. Encycloweedia. www.cdfa.ca.gov. Accessed 8/2004.
Bossard, CC. JM Randall, MC Hoshovsky. 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley: 81-86.


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

State-listed noxious weed in AZ, OR, and UT. Common in fields in western and central Canada. Found along watercourses in Canada. Invades bluebunch wheatgrass, Idaho fescue, and snowberry-rose communities in ID. Invades similar ecotypes in other areas. (May invade ecotypes not yet invaded in CA, information lacking.)


Sources of information:

DiTomaso, J, E. Healy. Weeds of California and Other Western States. Not yet published.
Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
Hill, Janice. 1999. Weed Report: Cardaria draba ssp. chalepensis. TNC Wildand Weed Survey.


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

Disturbed sites, moderately moist sites. A problem in crops. Roadsides, ditches. Needs moisture to spread and thrive. First collected in Chino, CA in 1918, probably introduced in alfalfa seed imported from Turkestan. Found in riparian-upland ecotones. Invades at least 2 major ecotypes in CA.


Sources of information:

DiTomaso, J, E. Healy. Weeds of California and Other Western States. Not yet published.
Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
CDFA. Encycloweedia. www.cdfa.ca.gov. Accessed 8/2004.
Bossard, CC. JM Randall, MC Hoshovsky. 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley: 81-86.


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

More frequent in the Sacramento Valley, southern San Joaquin Valley, and northern Siskiyou Co, but not common. Not nearly as widespread as either Cardaria draba or Cardaria pubescens. Occurs in less than 5% of the meadows, seeps, and riparian scrub in CA.


Sources of information:

DiTomaso, J, E. Healy. Weeds of California and Other Western States. Not yet published.
Mulligan, GA, JN Findlay. 1973. 3. Cardaria draba, C. chalepensis, and C. pubescens. The Biology of Canadian Weeds. Canadian Journal of Plant Science 54: 149-160.
Anonymous. Map of C. chalepensis in CA, 1935-1984.
Bossard, CC. JM Randall, MC Hoshovsky. 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley: 81-86.
Observational, Joe DiTomaso, 2004.


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 Yes
Fragments easily and fragments can become established elsewhere Yes
Resprouts readily when cut, grazed, or burned Yes
Total points: 11
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, 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 prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seepD, < 5%
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
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): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions