Alyssum murale_Ghislain118 Wikimedia
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Alyssum murale Risk Assessment

Common names: yellowtuft

Alyssum murale -- California

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Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
January 25, 2016
Evaluation Time (hrs): 
Not Recorded
Evaluation Status: 
Completed
Plant Information
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: 
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.
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: 
middle Europe, Colorado. Oregon, Utah, British Columbia, Ontario, Quebec.
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 Oregon, which is similar to California.
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: 
On Oregon noxious weed list, after escaped from phytoremediation project for a nickel mine. Reported more than a mile from planted site. Masses of plants located along roads. Spreading in the Illinois Valley, OR. Habitats where growing include disturbed sites as well as undisturbed native plant community hundreds of feet from trails or roads. Studies showed that they are capable of growing on serpentine soils.
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: 
Yes
Points: 
3
Confidence Level: 
High
Answer / Justification: 
Yes, Southern Oregon is similar to California based on Cal-IPC's climate map.
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: 
Alyssum corsicum is also a noxious weed in southern Oregon, which is similar to California's climate.
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: 
Native range is temperate Asia (Armenia; Azerbaijan; Georgia; Ciscaucasia, Turkey) , eastern and southeastern Europe (Moldova; Ukraine; Albania; Bosnia and Herzegovina; Bulgaria; Greece; Macedonia; Montenegro; Romania; Serbia). Based on the native range and points on GBIF (http://www.gbif.org/species/3045111), more than half of the areas match California based on Cal-IPC's climate map.
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: 
Very High
Answer / Justification: 
Creating monocultures in small areas in Oregon (being removed before it can spread further). Photos in the Oregon Weed Risk Assessment show dense stands.
Reference(s): 
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
Low
Answer / Justification: 
Oregon did a thorough Weed Risk Assessment and did not mention fire as a risk, so I am answering no.
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: 
Medium
Answer / Justification: 
Likely toxic to livestock (and maybe wildlife) due to its abiltiy to accumulate toxic metals. Moderate ingestion would likely cause poisoning.
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: 
High
Answer / Justification: 
Photos from Oregon Weed Risk Assessment show dense monocultures. Plants in Oregon grow up to 1m in height, taller than the 0.5-0.75m reported from the native range. Plants grow with multiple woody stems. Based on height and the woody stems, I am answering yes that it could slow movement of humans or animals.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
A woody shrub, so vegetative reproduction seems unlikely.
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: 
Medium
Answer / Justification: 
A woody shrub, so this ability seems unlikely.
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: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Produce "hundreds" of seeds, maybe thousands. Germination described as "prolific." Research found 92% seedling survival rates on nickel-rich soil under field conditions.
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: 
In a greenhouse trial, seeds germinated in one week.
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: 
Reproduces within one to two years.
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: 
Yes
Points: 
1
Confidence Level: 
Medium
Answer / Justification: 
Newspaper article says it flowers and seeds throughout the year in Oregon but the official risk assessment did not describe this.
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: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
No mention of this. Fruits are papery, circular to oval flattened silicles with a single flattened seed, so they do not have obvious adaptations for animal dispersal.
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: 
Fruits are papery and light and easily blown by wind. Portions of the flower with attached fruit form miniature tumbleweeds dispersed by wind. Seeds are able to float when removed from covering.
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: 
Medium
Answer / Justification: 
Seeds have been shed from bales in Oregon. Infestation at a dam in Oregon is presumed to have developed from seeds carried on vehicle tires driven by employees traveling from infested sites. However, the seeds do not seem to have a mechanism for attaching to tires, clothes, etc.
Reference(s): 
Evaluation Notes

Alyssum corsicum is very similar to A. murale so the same PRE can be used for both. They are listed together in Oregon. Direct link to Oregon WRA: http://www.oregon.gov/ODA/shared/Documents/Publications/Weeds/PlantPestRiskAssessmentAlyssum.pdf

Strawn 2013 modeled  suitable area for Alyssum in part of southern Oregon and a small part of northern California. Her results showed that northern California is not suitable. Strawn, K. 2013. Unearthing the habitat of a hyperaccumulator: case study of the invasive plant yellowtuft (Alyssum; Brassicaceae) in Southwest Oregon, USA. Management of Biological Invasions. 4(3): 249–259. doi: http://dx.doi.org/10.3391/mbi.2013.4.3.07

Total PRE Score

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

PRE Score: 
21
Number of questions answered: 
20
Screener Confidence (%): 
78.0
PRE Content Access and Privacy
Evaluation visibility: 
Public - accessible to all site users

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