Plant Assessment Form

Arctotheca prostrata

Synonyms: Arctotheca calendula (infertile forms)

Common Names: capeweed; South African capeweed; cape dandelion; cape gold

Evaluated on: 12/21/04

List committee review date: 11/02/2005

Re-evaluation date:

Evaluator(s)

Elizabeth Brusati, project manager
California Invasive Plant Council
1442A Walnut St. #462, Berkeley, CA 94709
510-843-3902
edbrusati@cal-ipc.org
Peter J. Warner; ecologist
California State Parks
P. O. Box 603, Little River, CA 95456
707-937-9172; 707-937-2278
corylus@earthlink.net

List commitee members

Carla Bossard
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

Removed second scientific name, Arctotheca calendula (infertile forms), and added it to the synonym line 3/28/17. Ramona Robison

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 B Other Published Material
Impact?
Four-part score BBBD Total Score
B
1.2 ?Impact on plant community B. Moderate Other Published Material
1.3 ?Impact on higher trophic levels B. Moderate
1.4 ?Impact on genetic integrity D. None Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment C. Minor Observational
Invasiveness?
Total Points
13 Total Score B
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 B. Increasing less rapidly Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
B. Moderate Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal A. High Reviewed Scientific Publication
2.6 ? Potential for natural long-distance dispersal D. None
2.7 ?Other regions invaded B. Invades 1 or 2 ecological types Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. Low 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? B Other Published Material
Identify ecosystem processes impacted:

Light availability, water availability, space Creates a dense monoculture that blocks light. Aggressive competitor for water and space. Scoring as B because I'm not sure if space is considered an "ecosystem process,"or if this change is irreversible.


Sources of information:

Alvarez, M. 2000. Arctotheca calendula pp. 49-52 in Bossard, C. M., J. M. Randall, and M. C. Hoshovsky (ed.) Invasive plants of California's wildlands. University of California Press. Berkeley, CA.


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

Rapidly overgrows other species to form dense monocultures. Aggressive competitor for water and space.


Sources of information:

Alvarez, M. 2000. Arctotheca calendula pp. 49-52 in Bossard, C. M., J. M. Randall, and M. C. Hoshovsky (ed.) Invasive plants of California's wildlands. University of California Press. Berkeley, CA.


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

Eaten by livestock, but sometimes poisonous. Used for pollen by beekeepers in Australia (1). However, another reference claims it is not poisonous (2). Not known to be eaten by California wildlife or invetebrates (3). Scoring as B based on severe changes to plant community that could impact foraging by wildlife dependent on grasses, although there is no specific information on how capeweed invasion affects higher trophic levels.


Sources of information:

1. Anonymous. Cape weed. http://weeds.tassie.net.au/txts/capeweed.html
2. McIvor, J.G., and D. F. Smith. 1972. Competitive growth of capeweed (Arctotheca calendula) and some annual pasture species. Australian Journal of Experimental Agriculture and Animal Husbandry. 13:185-189
3. Alvarez 2000


Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

none no closely related native species


Sources of information:

Alvarez 2000


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

1. Common along roadsides and disturbed land in native habitat; appears to require either deliberate or incidental disturbance for establishment (2) I've never seen this plant in the wild in undisturbed areas, and in almost every case, the plant appears to have been dumped or planted where it is growing; I expect that it is highly dependent on human assistance for establishment in the wild (2).


Sources of information:

1. Wood, H. 1994. The introduction and spread of capeweed, Arctotheca calendula ( L.) Levyns (Asteraceae). Plant Protection Quarterly. 9:94-100
2. Warner, PJ. Personal observations. Marin, Sonoma, Mendocino Counties, 1996-2005. 707/937-2278; corylus@earthlink.net


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

A small plant can cover as much as 200 square feet in 1-2 years. If planted 1 foot apart for landscaping, plants will spread to full cover in 6 months.


Sources of information:

Alvarez 2000, citing gardening books


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

At least slowly increasing, since it is still planted in landscapes, and people still dump the plant along roads, where mowing facilitates its spread (1). Some individuals have also been known to plant this weed intentionally in wildland areas (2). Personal observations based on the widespread use of this plant in landscaping and debris-dumping (1).
2. Alvarez, M. 1996. Anecdotes from Golden Gate National Recreation Area, as told to P. Warner.


Sources of information:

Warner, PJ. Personal observations. Marin, Sonoma, Mendocino Counties, 1996-2005. 707/937-2278; corylus@earthlink.net


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

Alvarez 2000


Sources of information:

Introduced for horticulture. Still widely used in landscaping (1,3). Can be spread by mechanical equipment along roads (1,3). Most populations in southern Australia are near water, stockyards, or railways (2). Found in Cal-IPC nursery survey 2004


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

Introduced for horticulture. Still widely used in landscaping (1,3). Can be spread by mechanical equipment along roads (1,3). Most populations in southern Australia are near water, stockyards, or railways (2). Found in Cal-IPC nursery survey 2004


Sources of information:

1. Alvarez 2000
2. Wood 1994.
3. Warner, PJ. Personal observations. Marin, Sonoma, Mendocino Counties, 1996-2005. 707/937-2278; corylus@earthlink.net


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

All reproduction is vegetative, so no seeds available for dispersal. Seems to require human activity to be spread.


Sources of information:

Inferred from information in Alvarez 2000


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

1. southern Australia: "widespread and successful colonizer, responsible for significant economic losses to cropping and pasture industries, occupies regions with climate similar to its native South Africa" Scoring as B based on the fact that it is widespread in Australia, which has similar habitats to parts of California, but capeweed has not yet invaded areas such as the central valley where it has the potential to grow (2)


Sources of information:

1, Wood 1994
2. Alvarez 2000


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

As of 2000, was in Marin and Humboldt counties (1). Widespread along Sonoma and Mendocino coast, especially in disturbed coastal terrace prairie and seasonally wet areas (2). Could probably survive in most of California west of Sierra Nevada mountains.


Sources of information:

1. Alvarez 2000
2. Warner, PJ. Personal observations. Marin, Sonoma, Mendocino Counties, 1996-2005. 707/937-2278; corylus@earthlink.net


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

Most common in coastal prairie, especially adjacent to roads, trails, or historical homesteads or farms. Often seen adjacent to habitual roadside dumping sites. Also seen occasionally in coastal wetlands and coastal scrub, also adjacent to human-disturbed sites or domestic landscapes (1). Purely observational, but lots of observations.


Sources of information:

1. Warner, PJ. Personal observations. Marin, Sonoma, Mendocino Counties, 1996-2005. 707/937-2278; corylus@earthlink.net


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter No
Populations of this species produce seeds every year. No
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years No
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: 5
Total unknowns: 0
Total score: B?

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 prairieC, 5% - 20%
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swampD, < 5%
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): C

Infested Jepson Regions

Click here for a map of Jepson regions