Maytenus boaria_mayten_Lech Naumovich_cropped
Photo: Lech Naumovich

Maytenus boaria Risk Assessment

Common names: mayten

Maytenus boaria -- California

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Created by: Elizabeth D. Brusati
Created on: Friday, Jul 1st, 2016
Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
July 8, 2016
Evaluation Time (hrs): 
Not Recorded
Evaluation Status: 
Completed
Plant Information
Plant: 
Maytenus boaria
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: 
USDA does not list anywhere naturalized other than California. The Jepson Manual considers it naturalized in California. Information from the 2006 Cal-IPC Inventory review says that it is spreading from plantings in Berkeley, Marin County, and Angel Island (San Francisco Bay) and is difficult to eradicate. GBIF shows some points in New Zealand and one each in Australia, Spain and British Columbia. Banned in New Zealand in 2012 after listing as an invasive species.
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: 
USDA does not list anywhere naturalized other than California. The Jepson Manual considers it naturalized in California. Information from the 2006 Cal-IPC Inventory review says that it is spreading from plantings in Berkeley, Marin County, and Angel Island (San Francisco Bay) and is difficult to eradicate. GBIF shows some points in New Zealand and one each in Australia, Spain and British Columbia.Banned in New Zealand in 2012 after listing as an invasive species.
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: 
Banned in New Zealand in 2012 after listing as an invasive species.
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: 
Banned in New Zealand in 2012 after listing as an invasive species. However, it is not recorded from the areas in New Zealand that are similar to California (the center of the South Island). Comment from Eric Wrubel: I would answer this as yes, based on the reports I have received from Ring Mountain. Chilean mayten is established there, and has been described as spreading into native grasslands. This plant is sometimes dioecious, so some populations can reproduce sexually and vegetatively, as at Ring Mountain. It is less of a problem if the population it is not recruiting by seed.
Reference(s): 
5. Are other species of the same genus (or closely related genera) invasive in a similar climate?
Yes or No: 
No
Points: 
0
Confidence Level: 
Medium
Answer / Justification: 
Six other Maytenus species are listed in Randall 2012, mostly referenced as being from a 1986 list of problem plants in South Africa but they aren't on the South African invasive plants website. Answering no without stronger information, details on invasive impacts, and information on where in South Africa they grow.
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: 
Most of the native range in South America is not similar to California. The only other place where it seems to have escaped substantially is New Zealand, but not in areas similar to California. Initially answered no but changed based on comment from Joe DiTomaso, UC Davis: "I think this is a yes since it is already found in the region of consideration, California. Species already here and spreading are clearly adapted to the climate."
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: 
Very High
Answer / Justification: 
In New Zealand: Seedlings are able to grow quickly under dense shade in reasonably undisturbed areas. The root suckers eventually form dense colonies of stems. Plants can outcompete both native and exotic trees to form monocultures. It occurs in the understorey of native bush, and amongst scrub and grasses.
Reference(s): 
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
Very Low
Answer / Justification: 
Germinates profusely after fire (Jepson, Blackhall). Cattle grazing causes increased plant bulk density and increased percentage of fine fuel. It certainly seems to be adapted to fire but I have no information that it changes fire regimes. There is no mention of increased fire as an impact in the New Zealand invasive plant information. Answered No by default due to lack of information on changes to fire regimes.
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: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
No mention of toxicity. In its native range it is a highly palatable species for cattle.
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: 
Medium
Answer / Justification: 
This is a tree that can grow up to 50 ft tall (20 ft tall x 15 ft wide is typical at 12 years of age). It also produces a lot of side growth. I don't have specific information on how dense the thickets are but given it's growth habit and that it is serious enough to be banned in New Zealand, I am assuming yes.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Root suckers can form dense colonies of stems. Sunset says it is likely to produce suckers when the roots are disturbed.
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: 
Very High
Answer / Justification: 
This is a tree, so it seems unlikely that detached fragments would produce new plants.
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: 
Female plants produce fleshy orange-red seed capsules in autumn.
Reference(s): 
14. Does this plant produce copious viable seeds each year (> 1000)?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Medium
Answer / Justification: 
This seems possible since it grows up to 50 ft tall.
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: 
Low
Answer / Justification: 
Comment from Joe DiTomaso: "Sheffield’s Seed Company says that the seeds are easy to germinate so I think that this means there is significant germination the following season. I would give the confidence a medium or even low, but I would answer yes based on this."
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: 
Answer / Justification: 
A tree described as having slow to moderate growth. No information on time to maturity.
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: 
No
Points: 
0
Confidence Level: 
Very High
Answer / Justification: 
Flowers April to May in California, so less than three months.
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: 
It produces fleshy fruits that are dispersed by birds.
Reference(s): 
19. Are the plant’s propagules frequently dispersed long distance (>100 m) by wind or water?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
No obvious adaptations for wind or water dispersal.
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: 
Does not have obvious adaptations for this.
Reference(s): 
Evaluation Notes

USDA GRIN: https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=23511

Jepson: http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=77417

GBIF: http://www.gbif.org/species/3790726

Biosecurity New Zealand: http://www.biosecurity.govt.nz/pests/chilean-mayten

New Zealand Plant Conservation Network: http://www.nzpcn.org.nz/flora_details.aspx?ID=3460

Reviewed by Joe DiTomaso and Eric Wrubel.

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: 
19
Screener Confidence (%): 
78.9
PRE Content Access and Privacy
Organization: 
California Invasive Plant Council (Cal-IPC)
Evaluation visibility: 
Public - accessible to all site users

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