Stipa brachychaeta_Dean Kelch_CDFA
Photo by Dean Kelch

Stipa brachychaeta Risk Assessment

Common names: punagrass

Stipa brachychaeta -- California

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Evaluation Summary
Summary: 
General Evaluation Information
Date of Evaluation: 
January 25, 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: 
California and Australia
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 9 counties in 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: 
Listed as invasive in South Australia, Western Australia and Tasmania due to its effects on agriculture and pasture. Listed under synonym Stipa brachyaeta in Parsons and Cuthbertson, which says that it invades disturbed soils along roadsides, waste places, and streams, and run-down pastures. Answering no because does not seem to have impacts in natural areas.
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: 
Listed as invasive in South Australia, Western Australia and Tasmania due to its effects on agriculture and pasture. There are few locations in the Australian Herbarium, none from South Australia. The one point from Western Australia (Perth) matches California's climate. Confidence lower due to lack of information on where it's invasive.
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: 
If you consider genus Stipa (its synonym), yes. Stipa capensis invasive in California. Other species of Stipa are invasive in Australia.
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: 
Has a limited natural and invasive range but as most of the locations in Australia match California, I am answering yes. Native to Argentina.
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: 
No
Points: 
0
Confidence Level: 
High
Answer / Justification: 
Invades disturbed sites or alfalfa fields in California, so not really affecting natural areas. A weed of overgrazed pasture, agricultural, and disturbed sites in Australia.
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 any references.
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: 
Medium
Answer / Justification: 
Foliage unpalatable to livestock. In Australia, can seriously reduce the productivity of pastures. However, the references seem to indicate that it mostly invades pastures that are already poor quality.
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: 
Grows up to 1m or occasionally 1.5 m tall but no information on how dense it is or whether it creates "impenetrable" areas.
Reference(s): 
Reproductive Strategies
11. Does this species (or cultivar or variety) reproduce and spread vegetatively?
Yes or No: 
No
Points: 
0
Confidence Level: 
Very High
Answer / Justification: 
Reproduces by seed. No mention of any vegetative reproduction. Does not have creeping rhizomes.
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. No mention of any vegetative reproduction.
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: 
This species produces two types of seeds, chasmogamous (with pollination) and cleistogamous (self-pollinating). Lerner found that mature tillers of punagrass can produce 250 chasmogamous seeds and low (<20) numbers of cleistogamous seeds each. 30% of tillers had chasmogamous seeds. She also found that plants produced a mean 1215 to 1619 cleistogamous seeds (lower number in poor conditions; higher in good conditions). This is difficult to translate into simple numbers because her studies were comparing plants derived from the two types of seeds. However, based on these numbers, I'm answering yes.
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: 
Seeds germinate in autumn and grow over winter (Australia). Lerner tested dormancy breaking treatments on seeds (after a chilling experiment) and found low germination rates with or without the treatments (25% or lower). However, she cited another study that found 40% germination for the chasmogamous seeds falling on the soil surface.
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: 
High
Answer / Justification: 
Since it's a grass, it seems likely that it would produce seed 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: 
Medium
Answer / Justification: 
Flowers May to October in California. Could not find information on seed production. In Australia, flowering starts in late spring and continues through summer if moisture is available. Interpreting these together as a yes.
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: 
Cross-pollinated seeds are often dispersed after their awns become attached to animals, clothing, or vehicles. Fine hairs on awns and callus allow seeds to stick to wool, clothing, and other material.
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: 
Dispersed by water, particularly during floods. However, Parsons and Cuthbertson says that water is a minor component of 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: 
Yes
Points: 
1
Confidence Level: 
Very High
Answer / Justification: 
Awns attach to vehicles. Can also be spread by mowing or in contaminated agricultural products. Fine hairs on awns and callus allow seeds to stick to wool, clothing, and other material.
Reference(s): 
Evaluation Notes

In both California and Australia, this species is a weed of agricultural crops or highly disturbed areas. Invades mostly overgrazed pastures in Australia.

Direct link to Weeds of Australia evaluation (under a synonym): http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-060...

 

Total PRE Score

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

PRE Score: 
20
Number of questions answered: 
20
Screener Confidence (%): 
79.0
PRE Content Access and Privacy
Evaluation visibility: 
Public - accessible to all site users

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