Scolymus hispanicus_C030-14
Photo: UC Davis Weeds of California

Scolymus hispanicus Risk Assessment

Common names: goldenthistle

Scolymus hispanicus -- California

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Created by: Elizabeth D. Brusati
Created on: Thursday, Jan 28th, 2016
Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
January 28, 2016
Evaluation Time (hrs): 
Not Recorded
Evaluation Status: 
Completed
Plant Information
Plant: 
Scolymus hispanicus
Plant Material: 
If the plant is a cultivar, and if the cultivar's behavior differs from its parent's (behavior), explain how: 
Regional Information
Region Name: 
California
Climate Matching Map
These maps were built using a toolkit created in collaboration between GreenInfo Network, PlantRight, Cal-IPC, and Agricultural Sustainability Institute at UC Davis.
Link to Climate Matching Map: 
Climate Matching Maps PDF: 
Invasive History and Climate Matching
1. Has the species (or cultivar or variety, if applicable; applies to subsequent "species" questions) become naturalized where it is not native?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Besides California, naturalized in Alabama, Pennsylvania, New York, Australia (New South Wales, Victoria), Portugal, Canary Islands, Libya, Argentina, Chile.
Reference(s): 
2. Is the species (or cultivar or variety) noted as being naturalized in the US or world in a similar climate?
Yes or No: 
Yes
Points: 
2
Confidence Level: 
Very High
Answer / Justification: 
Naturalized in 4 California counties. Other areas similar to California are Portugal and the Canary Islands.
Reference(s): 
3. Is the species (or cultivar or variety) noted as being invasive in the U.S. or world?
Yes or No: 
Yes
Points: 
2
Confidence Level: 
Very High
Answer / Justification: 
Listed as a noxious weed in Victoria, Australia, where it invades grazing lands and "neglected areas". Considered a problem in Argentina and Chile.
Reference(s): 
4. Is the species (or cultivar or variety) noted as being invasive in the US or world in a similar climate?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
Listed as a noxious weed in Victoria, Australia. However, the locations where it is present in Victoria do not match California. Locations on GBIF from Australia are not a good match to California. There is only one location from Chile so I do not know how widespread it is or whether the locations match California.
Reference(s): 
5. Are other species of the same genus (or closely related genera) invasive in a similar climate?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Scolymus maculatus is a listed noxious weed in New South Wales (Moree Plains Council Area), in a section of NSW that matches California. Dense patches become impenetrable to livestock.
Reference(s): 
6. Is the species (or cultivar or variety) found predominately in a climate matching the region of concern?
Yes or No: 
Yes
Points: 
2
Confidence Level: 
High
Answer / Justification: 
The native range is northern Africa (Morocco, Algeria, Tunisia), western Asia, and southern and eastern Europe. Besides California, naturalized in Alabama, Pennsylvania, New York, Australia (New South Wales, Victoria), Portugal, Canary Islands, Libya, Argentina, Chile. Many of these areas match California. GBIF map = http://www.gbif.org/species/5403742
Reference(s): 
Impact on Native Plants and Animals
7. Does this plant displace native plants and dominate (overtop or smother) the plant community in areas where it has established?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Forms dense infestations in Australia.
Reference(s): 
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
No mention of this.
Reference(s): 
9. Is the plant a health risk to humans or animals/fish? Has the species been noted as impacting grazing systems?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Taproot and young shoots are edible to humans. Weed of grazing lands in Victoria, Australia. Not eaten by livestock because of the spines. Livestock avoid grazing close to plants. Answering yes because of impacts on livestock.
Reference(s): 
10. Does the plant produce impenetrable thickets, blocking or slowing movement of animals, livestock, or humans?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Dense infestations become almost impenetrable to grazing animals in Australia.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
No mention of this.
Reference(s): 
12. If naturally detached fragments from this plant are capable of producing new plants, is this a common method of reproduction for the plant?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
No mention of this.
Reference(s): 
13. Does the species (or cultivar or variety) commonly produce viable seed?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Reproduces by seed.
Reference(s): 
14. Does this plant produce copious viable seeds each year (> 1000)?
Yes or No: 
Points: 
Confidence Level: 
Very Low
Answer / Justification: 
No information
Reference(s): 
15. Is there significant germination (>25%) of seeds the next growing season, with no requirement of an infrequent environmental condition for seeds to germinate (i.e. fire) or long dormancy period?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Medium
Answer / Justification: 
Flowers in late spring and summer and seeds germinate in autumn, winter, and spring.
Reference(s): 
16. Does this plant produce viable seed within the first three years (for an herbaceous species) to five years (for a woody species) after germination?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Yes, can be a biennial.
Reference(s): 
17. Does this plant continuously produce seed for >3 months each year or does seed production occur more than once a year?
Yes or No: 
Points: 
0
Confidence Level: 
Very Low
Answer / Justification: 
Flowers are formed in late spring and summer. Unclear how long seeds are produced.
Reference(s): 
Dispersal
18. Are the plant’s propagules frequently dispersed long distance (>100 m) by mammals or birds or via domestic animals?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Spiny heads can be caught in wool (and therefore spread by sheep).
Reference(s): 
19. Are the plant’s propagules frequently dispersed long distance (>100 m) by wind or water?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Wind is important for dispersal. The plant breaks off at the ground and is blown long distances. Seeds also transported by water.
Reference(s): 
20. Are the plant’s propagules frequently dispersed via contaminated seed (agriculture or wildflower packets), equipment, vehicles, boats or clothing/shoes?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Spiny heads are caught in agricultural produce. Some spread by agricultural equipment.
Reference(s): 
Evaluation Notes

Reviewed by Gina Darin, Ca Dept of Water Resources and Steve Schoenig, CA Dept of Fish and Wildlife and CA Dept of Food and Agriculture (retired)

Total PRE Score

  • < 13 : accept (low risk of invasiveness)
  • 13 - 15 : evaluate further
  • > 15 : reject (high risk of invasiveness)

PRE Score: 
17
Number of questions answered: 
18
Screener Confidence (%): 
87.8
PRE Content Access and Privacy
Organization: 
California Invasive Plant Council (Cal-IPC)
Evaluation visibility: 
Public - accessible to all site users

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