Plant Assessment Form

Centaurea calcitrapa

Common Names: purple starthistle

Evaluated on: 5/22/03

List committee review date: 06/06/2003

Re-evaluation date:

Evaluator(s)

Joe DiTomaso
UC Davis
Weed Science Program, Robbins Hall, Univ. California, Davis CA 95616
530-754-8715
DiTomaso@vegmail.ucdavis.edu

List commitee members

Joe DiTomaso
Peter Warner
Alison Stanton
Carla Bossard
Cynthia Roye
Jake Sigg
Doug Johnson
Brianna Richardson

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Observational
Impact?
Four-part score CBBD Total Score
B
1.2 ?Impact on plant community B. Moderate Other Published Material
1.3 ?Impact on higher trophic levels B. Moderate Other Published Material
1.4 ?Impact on genetic integrity D. None Observational
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 B. Increases less rapidly Observational
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly Observational
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 Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Observational
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. 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 Observational
Identify ecosystem processes impacted:

Probably impacts water runoff and percolation, as well as soil erosion similar to spotted knapweed, but no work has been conducted to prove this. Plant structure similar to spotted knapweed which increases erosion.


Sources of information:

DiTomaso-Observational


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

Sources of information:

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

Sharp spines can discourage deer or rodent grazing, or reduce forage quality. Not palatable even in early stages of growth. In Australia, plants protect rabbits, which are also invasive.


Sources of information:

Amme, D. 1985. Fremontia 13:22-23; Anonymous. 1998. Technical Bulletin. Marin Co.. Agricultural Land Trust, 2 pp.; Parsons, W.T. and E.G. Cuthbertson. 1992. Noxious Weeds of Australia. Inkata Press, Sydney


Question 1.4 Impact on genetic integrity? D Observational

Probably none. No native Centaurea in California


Sources of information:

: DiTomaso-Observational


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
B Observational
Describe role of disturbance:

mainly in disturbed areas, but con invade annual grass dominated grasslands. Prefers heavier bottomland soils.


Sources of information:

Question 2.2 Local rate of spread with no management? B Observational
Describe rate of spread:

Spreading, but only slightly.


Sources of information:

: DiTomaso-Observational


Question 2.3 Recent trend in total area infested within state? B Observational
Describe trend:

Spreading slowly, but still confined to North Coast areas. Some new reports in other areas.


Sources of information:

: DiTomaso-Observational


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

Seed longevity unknown. Produces lots of seeds, recovers after damage.


Sources of information:

DiTomaso, J.M. and E.A. Healy. 2005. Weeds of California. DANR (pre-print)


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

Some movement by machinery, and along roadsides.


Sources of information:

Parsons, W.T. and E.G. Cuthbertson. 1992. Noxious Weeds of Australia. Inkata Press, Sydney; Anonymous. 1998. Technical Bulletin. Marin Co.. Agricultural Land Trust, 2 pp.


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

Some movement in water, but not typically moved very far by natural means. Also can act like a tumbleweed and disperse seed moderate distances.


Sources of information:

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

As far north as Washington and east to Utah. Also a problem in Australia, New Zealand, the Middle East, and South Africa. Pasture and cereal crop weed in Australia.


Sources of information:

Parsons, W.T. and E.G. Cuthbertson. 1992. Noxious Weeds of Australia. Inkata Press, Sydney; DiTomaso, J.M. and E.A. Healy. 2005. Weeds of California. DANR (pre-print)


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Observational

Primarily in grasslands, sometimes in wetter areas than yellow starthistle. Introduced nearl Vacaville, CA, in 1896.


Sources of information:

Amme, D. 1985. Fremontia 13:22-23; : DiTomaso-Observational


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

Major infestations in Marin, Napa, Solano, and Sonoma counties, but found in other areas of the state. Mainly in grasslands.


Sources of information:

Woods, D.M., D.A. Mayhew and J.M. Gendron. 2000. CDFA Biological Cotnrol Program 1999. pp. 78-79


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 Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 8
Total unknowns: 1
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
chaparralC, 5% - 20%
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairieD, < 5%
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
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): C

Infested Jepson Regions

Click here for a map of Jepson regions

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