Paspalum urvillei_S45-13
Photo courtesy UC Davis Weeds of California

Paspalum urvillei Risk Assessment

Common names: Vasey's grass

Paspalum urvillei -- California

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Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
June 23, 2016
Evaluation Time (hrs): 
2 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: 
Naturalized in California. Present in 18 counties according to Calflora. Naturalized in China, Japan, India, Indonesia, Sri Lanka, Thailand, Vietnam, Australia, southern Africa, southwestern Europe, Central America, the Carribean and North America.
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 California. Present in 18 counties according to Calflora. There are many points in GBIF, including areas of Europe, South Africa and Australia that are 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: 
High
Answer / Justification: 
It invades and establishes in highly disturbed natural ecosystems where it grows in dense stands, displacing indigenous vegetation and altering the lower strata. It is listed as invasive in China, Japan, parts of Africa, United States, Puerto Rico and Australia (CABI Invasive Species Compendium).
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: 
It invades and establishes in highly disturbed natural ecosystems where it grows in dense stands, displacing indigenous vegetation and altering the lower strata. It is listed as invasive in China, Japan, parts of Africa, United States, Puerto Rico and Australia (CABI Invasive Species Compendium). There are many points in GBIF, including areas of Australia with climate similar to California.
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: 
Paspalum dilatatum is a closely related grass which is also widely naturalized due to its use as a pasture grass. It is also invasive in some Pacific Islands, Hawaii, Australia, Europe and South Africa.
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: 
Based on locations in GBIF and description in CABI, it occurs in many climatic areas that match California California. Map: http://www.gbif.org/species/2705650
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 Hawai‘i, grows in dense stands in mesic areas along forest roads, trails and open disturbed areas at low to mid-elevations, where it displaces native vegetation.
8. Is the plant noted as promoting fire and/or changing fire regimes?
Yes or No: 
No
Points: 
0
Confidence Level: 
Low
Answer / Justification: 
No information is available on this question.
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: 
P. urvilli is used as a forage grass so is not toxic to livestock and promotes grazing.
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: 
High
Answer / Justification: 
Plants are up to 220 cm tall and are perennial grasses so would not form impenetrable thickets.
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: 
It spreads both by seed and by rhizome.
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: 
It spreads both by seed and by rhizome.
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: 
Propagates by seed. Plants are able to produce seed either under open- or selfpollination (Caponio).
Reference(s): 
14. Does this plant produce copious viable seeds each year (> 1000)?
Yes or No: 
Yes
Points: 
1
Confidence Level: 
High
Answer / Justification: 
More than 25,000 seeds produced per plant.
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: 
High
Answer / Justification: 
Abundant seed set in the second or third year of sowing. Mature plant produces viable propagules for at least 3 years, but unlikely to be more than 10 years. The information at this website (Grassland Species Profiles) suggests that the majority of the seeds from any given year germinate. There is no mention of dormancy. http://www.fao.org/ag/AGP/AGPC/doc/Gbase/data/Pf000295.HTM
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: 
Abundant seed set in the second or third year of sowing.
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: 
Points: 
Confidence Level: 
Answer / Justification: 
Length of seed production is not mentioned in references, but flowering occurs from June to December (Jepson).
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: 
This species reproduces mainly by seed, which are dispersed by wind, water, animals, vehicles, machinery, and in contaminated soil and agricultural produce.
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: 
This species reproduces mainly by seed, which are dispersed by wind, water, animals, vehicles, machinery, and in contaminated soil and agricultural produce.
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: 
This species reproduces mainly by seed, which are dispersed by wind, water, animals, vehicles, machinery, and in contaminated soil and agricultural produce. The number of seeds per kg is 970,000, making this a likely pathway for unintentional introduction in hay bales or seed mixes. Proven ability to disperse greater than one kilometer (Agriculture Victoria).
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: 
21
Number of questions answered: 
19
Screener Confidence (%): 
82.1
PRE Content Access and Privacy
Evaluation visibility: 
Public - accessible to all site users

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