Plant Assessment Form

Arctotheca calendula (fertile forms)

Synonyms: Arctotheca calendulacea (R. Br.) Lewin, Arctotis calendula L.; Cryptostemma calendulaceum (L.) R.Br

Common Names: fertile capeweed

Evaluated on: 12/9/04

List committee review date: 11/02/2005

Re-evaluation date:

Evaluator(s)

Ed Finley
California Dept. of Food and Agriculture
20235 Charlanne Dr., Redding, CA. 96002
530-224-2425, fax 530-224-2427
efinley@cdfa.ca.gov

List commitee members

Carla Bossard
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

Two forms of capeweed occur in California, a fertile seed producing form with limited distrubtion in the state and a sterile form available from nurserys. The fertile form is currently A-rated by CDFA, but the sterile form is not rated. The fertile form was first intercepted as a contaminant of Australian subterranean clover seed in 1974 and the first established infestation was reported in 1988 on a dairy in Humboldt County (Barbe, Doug. 1988. CDFA Pest Detection Advisory, PD33-88). This assessment will address the fertile form.

Removed second scientific name, Arctotheca calendula (without fertile form), 3/28/17. Ramona Robison

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? Alert
Documentation? 3.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Reviewed Scientific Publication
Impact?
Four-part score CBDD Total Score
B
1.2 ?Impact on plant community B. Moderate Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels D. Negligible Reviewed Scientific Publication
1.4 ?Impact on genetic integrity D. None Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment C. Minor Reviewed Scientific Publication
Invasiveness?
Total Points
11 Total Score B
2.2 ?Local rate of spread with no management B. Increases less 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 Other Published Material
2.5 ?Potential for human-caused dispersal A. High Reviewed Scientific Publication
2.6 ? Potential for natural long-distance dispersal D. None Observational
2.7 ?Other regions invaded C. Already invaded Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Reviewed Scientific Publication
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 Reviewed Scientific Publication
Identify ecosystem processes impacted:

Capeweed probably impacts soil moisture and nutrient avilability. Capeweed infestations in agriculture may attain percent plant cover ratios approaching 100%. Such a dominance would likely affect soil moisture and nutrient availablity to the detrement of other species, but capeweed does not seem to compete well in wildland situations, thus it would normally pose only a minor alteration of these ecosystem processes.


Sources of information:

McIvor, J.G.; Smith D.F. 1973. Competitive growth of capeweed, Arctotheca calendula, and some annual pasture species. Australian Journal of ExperimentalAgriculture & Animal Husbandry. 13(61): 185-189.
Anonymous. Capeweed Arctotheca calendula. Http://weeds.tassie.net.au//txts/capeweed.html. Accessed on 8/16/1999
Finley, Ed. 2004. Personal observations of fertile capeweed on a Humboldt County dairy, 2001 to present. 530-224-2425 efinley@cdfa.ca.gov


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

Capeweed seems to be a relatively poor competitor with native species, but if established may pose a moderate impact on native plant communities. Capeweed has the potential to invade disturbed areas (bare ground) and establish nearly pure stands, thereby excluding native plants from re-colonizing such areas and possibly expanding into surrounding plant communities. Again, capeweed seems to be a relatively poor competitor, thus posing a moderate threat.


Sources of information:

McIvor, J.G.; Smith D.F. 1973. Competitive growth of capeweed, Arctotheca calendula, and some annual pasture species. Australian Journal of ExperimentalAgriculture & Animal Husbandry. 13(61): 185-189
Eaton, Ronnie. Alameda County Dept. of Agriculture. 2004. Obersavation on fertile capeweed at a private ranchette in San Mateo County, 2003 to 2004. Personal communication, 02/28/03. (510)670-5232.
Finley, Ed; Griffin, Denis; Oliver, Brad. Personal observations on a fertile capeweed infestation at a vineyard in Monterey County, April, 2001. 530-224-2425, efinley@cdfa.ca.gov


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

Fertile capeweed probably would have little effect on higher trophic levels. Since fertile capeweed is distributed mainly in agricultural situations, its impact on higher trophic levels would be negligible. Though not preferred, stock may feed on fertile capeweed.


Sources of information:

Anonymous. Capeweed Arctotheca calendula. Http://weeds.tassie.net.au//txts/capeweed.html. accessed on 8/16/1999


Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

There are no reports of fertile capeweed hybridization in California. There are no native species of Arctotheca in California.


Sources of information:

Hickman, James C., ed. 1993. The Jepson Manual Higher Plants of California. University of California Press, Berkeley and Los Angeles, California


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

It appears that fertile capeweed needs anthropogenic disturbance to establish. Distributions of fertile capeweed are generally in agricultural situations, particularly swards, pastures, and vineyards. There is very little spread into wildland situations without some disturbance, typically caused by agricultural practices (cultivation and transportation of stock fodder) or actual planting of specimens.


Sources of information:

Wood, Helen. 1994. The Introduction and spread of Capeweed, Arctotheca calendula, (l.) Levyns (Asteraceae) in Australia. Plant Protection Quarterly. 9(3): 94-100.
Eaton, Ronnie. Alameda County Dept. of Agriculture. 2004. Obersavation on fertile capeweed at a private ranchette in San Mateo County, 2003 to 2004. Personal communication, 02/28/03. (510)670-5232.
Finley, Ed; Griffin, Denis; Oliver, Brad. Personal observations on a fertile capeweed infestation at a vineyard in Monterey County, April, 2001. 530-224-2425, efinley@cdfa.ca.gov


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

Fertile capeweed is still only locally distributed in California and has increased its population very slowly, if at all. In Australia, capeweed seems to have the potential for further spread, but apparently in agriculture. In limited disjunct California populations of fertile capeweed, there is little indication of spread ito wildland situation. In Australia, capeweed is still spreading in agriculture.


Sources of information:

Wood, Helen. 1994. The Introduction and spread of Capeweed, Arctotheca calendula, (l.) Levyns (Asteraceae) in Australia. Plant Protection Quarterly. 9(3): 94-100.
Barbe, Doug. 1988. CDFA, Division of Plant Industry, Pest Detection Advisory, PD33-88.
Barbe, Doug. 1990. CDFA, Division of Plant Industry, Pest Detection Advisory, PD30-90.
Barbe, Doug. 1992. CDFA, Division of Plant Industry, Pest Detection Advisory, PD16-92.
Hrusa, Fred. 1999. CDFA, Division of Plant Indusrty, Pest and Damage Record, 1237670.
Hrusa, Fred, 2001. CDFA, Division of Plant Industry, Pest and Damage Record, P114622.
Finley, Ed; Griffin, Denis; Oliver, Brad. Personal observations on a fertile capeweed infestation at a vineyard in Monterey County, April, 2001. 530-224-2425, efinley@cdfa.ca.gov


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

Disjunct California populations do not seem to be spreading and are declining only with repeated treatments (hand removal or herbicidal). Very small populations in the GGNRAand Point Reyes National Seashore have been eradicated by hand removal. Herbicidal treatments on the larger populations at a dairy in Humboldt County and a vineyard in Monterey County have had only limited success.


Sources of information:

Barbe, Doug. 1990. CDFA, Division of Plant Industry, Pest Detection Advisory, PD30-90.
Barbe, Doug. 1992. CDFA, Division of Plant Industry, Pest Detection Advisory, PD16-92.
Finley, Ed. 2004. Personal observations of fertile capeweed on a Humboldt County dairy, 2001 to present. 530-224-2425 efinley@cdfa.ca.gov
Finley, Ed; Griffin, Denis; Oliver, Brad. Personal observations on a fertile capeweed infestation at a vineyard in Monterey County, April, 2001. 530-224-2425, efinley@cdfa.ca.gov


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

Hickman, James C., ed. 1993. The Jepson Manual Higher Plants of California. University of California Press, Berkeley and Los Angeles, California
DiTomasso, J. Healy E. Weeds of California and other Western States. (as yet unpublished)


Sources of information:

Fertile capeweed may disperse via contaminated seed, hay, fodder, sheep wool, horses, and through direct movement by humans. Fertile capeweed was originally introduced into California via contaminated alfalfa seed, and in Australia by practically all of the above mentioned routes.


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

Fertile capeweed may disperse via contaminated seed, hay, fodder, sheep wool, horses, and through direct movement by humans. Fertile capeweed was originally introduced into California via contaminated alfalfa seed, and in Australia by practically all of the above mentioned routes.


Sources of information:

Wood, Helen. 1994. The Introduction and spread of Capeweed, Arctotheca calendula, (l.) Levyns (Asteraceae) in Australia. Plant Protection Quarterly. 9(3): 94-100.
Barbe, Doug. 1988. CDFA, Division of Plant Industry, Pest Detection Advisory, PD33-88.


Question 2.6 Potential for natural long-distance dispersal? D Observational
Identify dispersal mechanisms:

It appears that California infestations of fertile capeweed have not spread more than 1 km. The California fertile capeweed populations have been relatively stable. Human-caused dispersal seems to be the primary means of spread. There may be some movement of seed, which is covered by dense wooly hairs, by animals, wind, or water, but so far this is limited.


Sources of information:

Finley, Ed. 2004. Personal observations of fertile capeweed on a Humboldt County dairy, 2001 to present. 530-224-2425 efinley@cdfa.ca.gov
Finley, Ed; Griffin, Denis; Oliver, Brad. Personal observations on a fertile capeweed infestation at a vineyard in Monterey County, April, 2001. 530-224-2425, efinley@cdfa.ca.gov


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

Fertile capeweed is an invasive species in agricultural regions in Australia. Fertile capeweed is a pest in swards of Australia, presumably equivelant to coastal praire and scrub ecological types converted to agriculture in California.


Sources of information:

Wood, Helen. 1994. The Introduction and spread of Capeweed, Arctotheca calendula, (l.) Levyns (Asteraceae) in Australia. Plant Protection Quarterly. 9(3): 94-100.
Barbe, Doug. 1988. CDFA, Division of Plant Industry, Pest Detection Advisory, PD33-88.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Reviewed Scientific Publication

It appears that fertile capeweed is capable of moderate tendency to invade different ecological types. In California, fertile capeweed has a distribution so far limited to coastal praire (Humboldt County) and costal scrub (Monterey County). In Australia, it has invaded agricultural areas and is most successful in regions with climates similar to its range in South Africa.


Sources of information:

Wood, Helen. 1994. The Introduction and spread of Capeweed, Arctotheca calendula, (l.) Levyns (Asteraceae) in Australia. Plant Protection Quarterly. 9(3): 94-100.
Barbe, Doug. 1988. CDFA, Division of Plant Industry, Pest Detection Advisory, PD33-88.


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

Fertile capeweed has not dominated any of the ecological types in which it occurs. So far, fertile capeweed is limited to two ecological types in California and it has not achieved dominance in either.


Sources of information:

Barbe, Doug. 1988. CDFA, Division of Plant Industry, Pest Detection Advisory, PD33-88.
Barbe, Doug. 1990. CDFA, Division of Plant Industry, Pest Detection Advisory, PD30-90.
Barbe, Doug. 1992. CDFA, Division of Plant Industry, Pest Detection Advisory, PD16-92.
Hrusa, Fred. 1999. CDFA, Division of Plant Indusrty, Pest and Damage Record, 1237670.
Hrusa, Fred, 2001. CDFA, Division of Plant Industry, Pest and Damage Record, P114622.


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 Unknown
Seeds remain viable in soil for three or more years Unknown
Viable seed produced with both self-pollination and cross-pollination Unknown
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: 8
Total unknowns: 3
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 scrubD, < 5%
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 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)
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

  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest