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Hypericum androsaemum Risk Assessment

Common names: sweet-amber

Hypericum androsaemum -- California

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Created by: Elizabeth D. Brusati
Created on: Wednesday, Jan 20th, 2016
Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
January 20, 2016
Evaluation Time (hrs): 
Not Recorded
Evaluation Status: 
Completed
Plant Information
Plant: 
Hypericum androsaemum
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: 
Southern Africa, Australia, New Zealand, OR, WA, CA, British Columbia, Chile according to USDA-ARS.
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: 
Medium
Answer / Justification: 
One record of naturalization from Santa Cruz County in 1980.
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 a noxious weed in Victoria, Australia and Western Australia. "Occurs but is not important" in New South Wales, except for a few areas where it is locally abundant. Parsons and Cuthbertson don't describe ecological impacts, except to say that it encroaches on pastures from shady sites on forest edges. Invasive in New Zealand (on list of weeds controlled by land managers due to environmental impacts) but no information on where. Species not listed in Global Biodiversity Information Facility maps.
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: 
Several of the points in New Zealand are in areas that match California, based on Cal-IPC's climate map (in the mountains on the South Island). Locations in Victoria and New South Wales match California. Listed confidence as medium because of uncertainty about the level of impacts.
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: 
Very High
Answer / Justification: 
Hypericum canariense and Hypericum perforatum are 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: 
High
Answer / Justification: 
Native range includes northern Africa and temperate Asia, in areas that mostly match California. Native range in Europe spreads over areas that match California and others that do not. Naturalized areas in Australia are mostly similar to California; in New Zealand mostly do not match California. Oregon and much of British Columbia match California as does Lesotho (southern Africa).
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: 
In Victoria, overgrazed hillsides have been covered. It can also establish in undisturbed areas and competes strongly with native plants. Example of one population in Victoria extending hundreds of meters from a road into undisturbed brush.
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 so default answer is 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: 
Low
Answer / Justification: 
Was previously used as a medicinal plant. Has been suspected of poisoning cattle but this is not well documented. Plant is unpalatable and rarely eaten so poisoning not a significant problem to livestock. Answering yes due to suspected poisoning and being unpalatable.
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: 
Can form dense stands covering hillsides. Grows about 1m tall, which seems tall enough to block movement.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
Medium
Answer / Justification: 
Reproduces by seed. Also noted to reproduce vegetatively in its native range (http://e-ecodb.bas.bg/rdb/en/vol1/Hypandro.html).
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: 
Reproduces by seed
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: 
Medium
Answer / Justification: 
The Washington Noxious Weed Board website says that Hypericum perforatum can produce 100,000 seeds each year (http://www.nwcb.wa.gov/weeds/common-st-johnswort). This seems reasonable given the size of the seeds, capsules, and number of flowers. From my experience with H. canariense and other Hypericum species it seems highly likely that H. androsaeumum would produce >1,000 seeds in a year (Tim Hyland pers. comm.).
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: 
Fruit ripen in late summer, seeds germinate in autumn (I'm assuming this means the seeds from the same year, no mention of overwintering requirement).
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: 
Plants flower when they are 18 months to 2 years old.
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: 
Medium
Answer / Justification: 
In Australia, flowers are produced late spring to early summer and fruit ripen in late summer. In California, where it's an occasional escape from gardens, flowering time listed as June, so answering no based on that information.
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: 
Medium
Answer / Justification: 
Spread is mostly by seed. Not specially adapted for dispersal but its small size and large numbers allow it to contaminate equipment, animals, water, and mud.
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: 
Spread is mostly by seed. Not specially adapted for dispersal but its small size and large numbers allow it to contaminate equipment, animals, water, and mud.
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: 
Spread is mostly by seed. Not specially adapted for dispersal but its small size and large numbers allow it to contaminate equipment, animals, water, and mud.
Reference(s): 
Evaluation Notes

None, just testing.

Total PRE Score

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

PRE Score: 
22
Number of questions answered: 
20
Screener Confidence (%): 
71.0
PRE Content Access and Privacy
Organization: 
California Invasive Plant Council (Cal-IPC)
Evaluation visibility: 
Public - accessible to all site users

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