Heliotropium amplexicaule_C071-11
Photo courtesy UC Davis Weeds of California

Heliotropium amplexicaule Risk Assessment

Common names: clasping heliotrope

Heliotropium amplexicaule -- California

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Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
July 1, 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: 
USDA GRIN says naturalized but does not specify where. Widely naturalized in eastern and southeastern Australia. Naturalized in California (present in four counties) and in the southern and eastern US.
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: 
Widely naturalized in eastern and southeastern Australia, including areas similar to California. In Australia, it is a weed of pastures, crops and fallows, roadsides, footpaths, lawns, parks, gardens, disturbed sites, waste areas, open woodlands and grassland. Naturalized in California (present in four counties)
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: 
High
Answer / Justification: 
From Queensland website: Blue heliotrope (Heliotropium amplexicaule) is regarded as an environmental weed in New South Wales, Queensland and South Australia. Though it is mainly seen as a weed of roadsides, disturbed sites and pastures, it is also listed as a priority environmental weed in three Natural Resource Management regions. It displaces native species, particularly in overgrazed or otherwise disturbed areas, and prefers sandy soils. It is prohibited entry into Western Australia and designated a "locally controlled weed" in New South Wales.
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: 
From Queensland website: Blue heliotrope (Heliotropium amplexicaule) is regarded as an environmental weed in New South Wales, Queensland and South Australia. Though it is mainly seen as a weed of roadsides, disturbed sites and pastures, it is also listed as a priority environmental weed in three Natural Resource Management regions. It displaces native species, particularly in overgrazed or otherwise disturbed areas, and prefers sandy soils.
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: 
Heliotropium europaeum (common heliotrope) is a listed noxious weed in Western Australia because of the economic damage it causes in grazing areas. It is toxic to sheep, cattle, and horses. However, it is not considered an aggressive plant because other species can outcompete it.
Reference(s): 
6. Is the species (or cultivar or variety) found predominately in a climate matching the region of concern?
Yes or No: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
The species grows in some areas that are similar to California, but others that are not, such as the more tropical areas of eastern Australia and eastern South America, as well as the southeastern United States.
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: 
From Queensland website: Blue heliotrope (Heliotropium amplexicaule) is regarded as an environmental weed in New South Wales, Queensland and South Australia. Though it is mainly seen as a weed of roadsides, disturbed sites and pastures, it is also listed as a priority environmental weed in three Natural Resource Management regions. It displaces native species, particularly in overgrazed or otherwise disturbed areas, and prefers sandy soils. Near Sydney, it occurs in sites occupied by the endangered herb Zieria obcordata.
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 information so defaulting to 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: 
Very High
Answer / Justification: 
In Warrumbungle National Park, New South Wales, this species invades grazing areas and outcompetes species that are better forage. It occupies 110,000 hectares (270,000 ac) of New South Wales. It's also considered a threat to rangeland biodiversity in Queensland. It is eaten by cattle in Queensland even when other forage is available, but causes liver damage. Cases of jaundice and death are regularly reported.
Reference(s): 
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: 
This species is an herb with creeping, somewhat prostrate stems that grows 20-60cm tall (only 30cm according to the Australia reference) so impenetrable thickets in our definition seem unlikely.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
This plant reproduces mostly by seed, but can also produce shoots from its roots and establish from root fragments. It easily regenerates from root fragments.
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: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
Can establish from root fragments.
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: 
Produces seeds. The fruit is a nutlet.
Reference(s): 
14. Does this plant produce copious viable seeds each year (> 1000)?
Yes or No: 
Points: 
Confidence Level: 
Answer / Justification: 
Produces many seeds but I don't have information on numbers.
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: 
Points: 
Confidence Level: 
Answer / Justification: 
No information
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: 
Medium
Answer / Justification: 
As it's a small herb that is described as a prolific seed producer, I would assume it can produce seeds within three 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: 
High
Answer / Justification: 
Flowers all year in California. In frost-free areas of Australia, the plant can flower at any time of the year.
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: 
High
Answer / Justification: 
The sticky seeds can be dispersed by animals and pass through the gut of animals unharmed.
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: 
High
Answer / Justification: 
The seeds can be dispersed 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: 
High
Answer / Justification: 
Root fragments can be spread by farm equipment and seeds can be spread by vehicles.
Reference(s): 
Evaluation Notes
Total PRE Score

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

PRE Score: 
19
Number of questions answered: 
18
Screener Confidence (%): 
80.0
PRE Content Access and Privacy
Evaluation visibility: 
Public - accessible to all site users

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