Plant Assessment Form

Agrostis avenacea

Synonyms: Agrostis retrofracta

Common Names: Pacific bentgrass

Evaluated on: 27-Jul-04

List committee review date: 27/08/2004

Re-evaluation date:

Evaluator(s)

Joseph M. DiTomaso
University of California, Davis
Weed Science Program, Robbins Hall, Davis, CA 95616
530-754-8715
ditomaso@vegmail.ucdavis.edu

List commitee members

Jake Sigg
Alison Stanton
Peter Warner
Cynthia Roye
John Randall
Joe DiTomaso

General Comments

Very little information is available on Pacific bentgrass. It has become naturalized in many areas of the statte, country and world, but does not appear to be a significant problem.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Observational
Impact?
Four-part score CCUD Total Score
C
1.2 ?Impact on plant community C. Minor Observational
1.3 ?Impact on higher trophic levels U. Unknown
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Observational
Invasiveness?
Total Points
10 Total Score C
2.2 ?Local rate of spread with no management C. Stable Observational
2.3 ?Recent trend in total area infested within state C. Stable Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
B. Moderate Other Published Material
2.5 ?Potential for human-caused dispersal C. Low Other Published Material
2.6 ? Potential for natural long-distance dispersal C. Rare Reviewed Scientific Publication
2.7 ?Other regions invaded B. Invades 1 or 2 ecological types Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
C. Limited Other Published Material
Distribution?
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Observational

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? C Observational
Identify ecosystem processes impacted:

No known effects on abiotic ecosystem processes. Populations do not appear to be significant enough to impact abiotic ecosystems.


Sources of information:

DiTomaso, J.M. observational 2004


Question 1.2 Impact on plant community composition,
structure, and interactions?
C Observational
Identify type of impact or alteration:

Does not appear to form a dense population that impacts plant communities.


Sources of information:

DiTomaso, J.M. observational 2004


Question 1.3 Impact on higher trophic levels? U
Identify type of impact or alteration:

Unknown, but no impacts yet observed.


Sources of information:

Question 1.4 Impact on genetic integrity? D Other Published Material

Although there are some native species of Agrostis in California, there is no report of hybridization with Agrostis avenacea or other non-native species.


Sources of information:

Hickman, J.C. (ed.). 1993. The Jepson Manual. UC Press.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
C Observational
Describe role of disturbance:

Often found in disturbed roadside environments, but has been observed to be in other sites, including ponds and open grassy areas, particularly with some moisture.


Sources of information:

DiTomaso, J.M. observational 2004


Question 2.2 Local rate of spread with no management? C Observational
Describe rate of spread:

Can be found in wildlands, but does not appear to spread readily or to form very dense stands.


Sources of information:

DiTomaso, J.M. observational 2004


Question 2.3 Recent trend in total area infested within state? C Observational
Describe trend:

Does not appear to be expanding its range in the state.


Sources of information:

DiTomaso, J.M. observational 2004


Question 2.4 Innate reproductive potential? B Other Published Material
Describe key reproductive characteristics:

Very little is known of the biology of this species. It is a shortlived bunchgrass perennial which produces numerous small seeds.


Sources of information:

Hickman, J.C. (ed.). 1993. The Jepson Manual. UC Press.; DiTomaso and Healy. 2005. Weeds of California and other western states. UC ANR (in press); DiTomaso, J.M. observational 2004


Question 2.5 Potential for human-caused dispersal? C Other Published Material
Identify dispersal mechanisms:

Thought that the inflorescences are picked up by vehicles and dispersed long distances, but this is probably fairly rare.


Sources of information:

Nava-Rojo and Gomez-Sanchez et al. 2002. Agrostis avenacea: first record for the Mexican flora. Sida Contributions to Botany 20(1):423-429.


Question 2.6 Potential for natural long-distance dispersal? C Reviewed Scientific Publication
Identify dispersal mechanisms:

Plants act like tumble weeds and the dried panicles are carried widely by wind and in the process dispere their seeds. Probably does not move by this mechanism over 1 km. May also move via water in canals and streams, but typically not found alongside these sites.


Sources of information:

Nava-Rojo and Gomez-Sanchez et al. 2002. Agrostis avenacea: first record for the Mexican flora. Sida Contributions to Botany 20(1):423-429.


Question 2.7 Other regions invaded? B Reviewed Scientific Publication
Identify other regions:

Reported from temporary and permanent ponds in Mexico. Not genererally found along ponds in California, so this may be a habitat that it can eventually spread into. Previously known from Australia, South Africa, Argentina, Chile, the Hawaiian Islands and most recently from Costa Rica. Native to the southern Pacific Islands. nter text here


Sources of information:

Nava-Rojo and Gomez-Sanchez et al. 2002. Agrostis avenacea: first record for the Mexican flora. Sida Contributions to Botany 20(1):423-429.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? C Other Published Material

Pacific bentgrass inhabits open, disturbed, often moist places on the southern North Coast, southern North Coast Ranges, Sierra Nevada foothills, Central Valley, Central-western region, and northern South Coast, to 300 m. It is especially invasive in vernal pool habitat in the San Diego area. Pacific bentgrass also occurs in Ohio, South Carolina, and Texas.


Sources of information:

DiTomaso and Healy. 2005. Weeds of California and other western states. UC ANR. (in press)


Question 3.2 Distribution/Peak frequency? D Observational
Describe distribution:

Not dominant or common in any community.


Sources of information:

DiTomaso, J.M. observational 2004


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter Yes
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years Unknown
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Unknown
Total points: 4
Total unknowns: 3
Total score: B?

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuaries
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairieD, < 5%
valley and foothill grasslandD, < 5%
Great Basin grassland
vernal poolD, < 5%
meadow and seepD, < 5%
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): C
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Cascade Range
  • Central West
  • Sonoran Desert
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest