Plecostachys serpyllifolia_Ron Vanderhoff
Photo by Ron Vanderhoff

Plecostachys serpyllifolia Risk Assessment

Common names: petite-licorice

Plecostachys serpyllifolia -- California

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Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
April 26, 2016
Evaluation Time (hrs): 
3 Hours
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: 
California, Portugal, and the Azores. In California, naturalized in alkaline wetlands and moist sandy or rocky alkaline to saline sites along the coast.
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: 
Portugal and the Azores are similar to California. Also naturalized in eight California counties. In California, naturalized in alkaline wetlands and moist sandy or rocky alkaline to saline sites along the coast. One grower in California decided to stop production because the plant was seen escaping into natural areas from gardens.
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: 
Medium
Answer / Justification: 
Listed as naturalized in Portugal and the Azores (but not necessarily invasive). Not aggressive in its native South Africa or in Portugal. However, in California it has been recorded displacing native plants in coastal southern California, including several species listed as rare by CNPS. Information sent to Cal-IPC watchlist said that the Navy has been eradicating the plant on their base at Point Mugu, but the growing population keeps reseeding the base, and is now spreading into areas of salt grass and Salt Marsh Bird's Beak.
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: 
Medium
Answer / Justification: 
Not aggressive in its native South Africa or in Portugal. However, in California it has been recorded displacing native plants in coastal southern California, including several species listed as rare by CNPS. Information sent to Cal-IPC watchlist said that the Navy has been eradicating the plant on their base at Point Mugu, but the growing population keeps reseeding the base, and is now spreading into areas of salt grass and Salt Marsh Bird's Beak.
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: 
No other species of Plecostachys listed in Global Compendium of Weeds. However, synonym genus Helichrysum contains Helichrysum petiolare (licorice plant), which is invasive in California.
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: 
Very High
Answer / Justification: 
South Africa (native range) and areas where naturalized match California. http://www.gbif.org/species/3149321
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: 
Medium
Answer / Justification: 
Not aggressive in its native South Africa or in Portugal. However, in California it has been recorded displacing native plants in coastal southern California, including several species listed as rare by CNPS. Information sent to Cal-IPC watchlist said that the Navy has been eradicating the plant on their base at Point Mugu, but the growing population keeps reseeding the base, and is now spreading into areas of salt grass and Salt Marsh Bird's Beak.
Reference(s): 
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
No mention of this. In native range it requires seasonally damp conditions although it is adapted to summer drought. In California, naturalizes in moist habitats (edge of wetlands) and is a facultative wetland plant.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
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: 
Dave's Garden says all parts of plant are toxic. Handling plant may cause skin irritation or allergic reaction. Plant has spines or sharp edges.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
10. Does the plant produce impenetrable thickets, blocking or slowing movement of animals, livestock, or humans?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
It is a shrub that grows 1m tall. Described as a small to medium, straggling shrub. Also described as a dense, low-growing shrub that can spread into non-irrigated areas. Not sure if it qualifies as impenetrable.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
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: 
Considered a sprawling perennial shrub or ground cover but I could not find specific information on reproduction. Because it's a shrub, vegetative reproduction seems unlikely.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
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: 
Seems unlikely given that it's a shrub.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
13. Does the species (or cultivar or variety) commonly produce viable seed?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Seeds are described as being easy to grow.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
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: 
Has a tendency to seed a lot in a garden and escape. Based on that, I'm assuming that it must be able to germinate pretty easily.
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: 
Points: 
Confidence Level: 
Very Low
Answer / Justification: 
No information
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: 
March to May in native South Africa. Flowers Feb - June in California so I am extrapolating that to count as more than three months of seed production.
Reference(s): 
South African National Biodiversity Institute (2012).  Plantz Africa.
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: 
Couldn't find information on dispersal in its native range or naturalized range. It doesn't seem to have obvious adaptations for animal dispersal so I am answering no.
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: 
Medium
Answer / Justification: 
Couldn't find specific information on dispersal in its native range or naturalized range. The seed has a pappus of approximately 20 bristles which could make it adapted for wind dispersal. Answering yes based on this but with medium confidence.
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: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
Couldn't find information on dispersal in its native range or naturalized range. Answering no because it does not seem to have obvious adaptations for this type of dispersal.
Reference(s): 
Evaluation Notes

Not listed in ARS GRIN database under the name or the synonym. Nothing listed in  Web of Science. Tried to find information from its native range on biology in the wild but had no luck.

The best information was from its native range in South Africa: http://pza.sanbi.org/plecostachys-serpyllifolia

Dave's Garden: http://davesgarden.com/guides/pf/go/55068/

San Marcos Growers: http://www.smgrowers.com/products/plants/plantdisplay.asp?plant_id=1295.

Reviewed by Irina Irvine, NPS Santa Monica Mountains Recreation Area, and Ramona Robison, independent botanist

FYI from Cark Cowan at Channel Islands National Park species found at Santa Rosa Island and possibly Santa Cruz Island: "When I first reported it at a Botanic Garden meeting (2008?) with Steve Junak we thought it was Helichrysum petiolare.  The latest find that Sangeet made at Skunk point was Plecostachys serpyllifolia.  Initially when it was reported we thought it was licorice plant but he identified it as Plecostachys serpyllifolia. We do have specimens of the material from SRI and possibly SCI."

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 (%): 
70.0
PRE Content Access and Privacy
Evaluation visibility: 
Public - accessible to all site users

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