Plant Assessment Form

Glyceria declinata

Common Names: mannagrass; sweetgrass; waxy mannagrass

Evaluated on: 7/18/05

List committee review date: 15/08/2005

Re-evaluation date:

Evaluator(s)

Elizabeth Brusati, project manager
California Invasive Plant Council
1442A Walnut St. #462, Berkeley, CA 94709
510-843-3902
edbrusati@cal-ipc.org

List commitee members

Jake Sigg
Cynthia Roye
Peter Warner
Joe DiTomaso

General Comments

This species has been thought to be the same as native Glyceria occidentalis. However, new taxonomic evidence shows that they are different species, and Carol Witham with CNPS says they differ in both habit and habitat.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? No Alert
Documentation? 2 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U
Impact?
Four-part score UBBU Total Score
B
1.2 ?Impact on plant community B. Moderate Observational
1.3 ?Impact on higher trophic levels B. Moderate Other Published Material
1.4 ?Impact on genetic integrity U. Unknown
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Reviewed Scientific Publication
Invasiveness?
Total Points
11 Total Score B
2.2 ?Local rate of spread with no management B. Increases less rapidly Observational
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly Other Published Material
2.4 ?Innate reproductive potential
(see Worksheet A)
B. Moderate Observational
2.5 ?Potential for human-caused dispersal U. Unknown
2.6 ? Potential for natural long-distance dispersal C. Rare Anecdotal
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Other Published Material
Distribution?
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. 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? U
Identify ecosystem processes impacted:

Good at denitrification and reduction of NO3- to ammonium. No evidence of this in wildland areas.


Sources of information:

Matheson F.E. et al. 2002. Fate of 15N-nitrate in unplanted, planted and harvested riparian wetland soil microcosms. Ecological Engineering 19: 249-264.


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

Can form monoclonal stands, especially in vernal pools with a high clay content. Displaces and shades out native vegetation, decreases germination of native forbs. Threatens endangered Sacramento orcutt grass (Orcuttia viscida) in pools where Glyceria has invaded.


Sources of information:

Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


Question 1.3 Impact on higher trophic levels? B Other Published Material
Identify type of impact or alteration:

Changes vernal pool food web towards more oppotunistic feeders. Reduces abundance of listed Brachiopods


Sources of information:

Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations
Proceedings of the 1998 Vernal Pool .


Question 1.4 Impact on genetic integrity? U

There are six species of native Glyceria in California. No information on hybridization.


Sources of information:

Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA enter text here


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

Likes wet, disturbed places. In California, occurs in vernal pools that are disturbed as well as those in good condition. In Poland, all habitats of G. declinata are moist, sodden, periodically flooded, subjected to moderate trampling or grazing. Typical areas are roadsides or paths over moist meadows and on the borders of ponds.


Sources of information:

Mirek, Z. and T. Zaluski. 1986. Glyceria-Declinata Breb. Gramineae in Poland Distribution and Habitats. Acta Societatis Botanicorum Poloniae 55(3): 505-516.
Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


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

Has increased during the last several years.


Sources of information:

Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


Question 2.3 Recent trend in total area infested within state? B Other Published Material
Describe trend:

A few years ago was seen only occasionally in Central Valley vernal pools, but now it occurs in many places, even pools that are relatively undisturbed.


Sources of information:

Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


Question 2.4 Innate reproductive potential? B Observational
Describe key reproductive characteristics:

Perennial, rhizomatous grass. Culms root at lower nodes.


Sources of information:

Glyceria key from Mary Barkworth, Utah State University.


Question 2.5 Potential for human-caused dispersal? U
Identify dispersal mechanisms:

No information.


Sources of information:

Question 2.6 Potential for natural long-distance dispersal? C Anecdotal
Identify dispersal mechanisms:

Seeds might be spread by sticking in mud on the feet of cows or birds.


Sources of information:

Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


Question 2.7 Other regions invaded? C Other Published Material
Identify other regions:

Native to Europe. Introduced in New Zealand. Also found in Nevada and New York.


Sources of information:

Shaw, W. B., and R. B. Allen. 2003. Ecological impacts of sea couch and saltwater paspalum in Bay of Plenty estuaries. DOC Science Internal Series 113. Department of Conservation, Wellington New Zealand. Available: http://www.doc.govt.nz/publications/004~science-and-research/DOC-Science-Internal-Series/PDF/DSIS113.pdf
Champion, P., J. Clayton, and D. Rowe. 2003. Lake Manager's Handbook: Alien Invaders. 2002. New Zealand Ministry of the Environment. Ref. ME444. Available: http://www.mfe.govt.nz/publications/water/lm-alien-invaders-jun02.pdf
USDA, NRCS. 2005. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.


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

Uncommon in moist canyons and meadows, also reported from Central Valley (GV) vernal pools, but genetic research is needed to confirm identify. Listed as "need more information" on Cal-IPC 1999 list.
Mary Barkworth at Utah State University has confirmed that it is a different species than native Glyceria occidentalis. May also invade freshwater marshes and moist swales.


Sources of information:

Clark, G.M., T. J. Roscoe, and M. J. Van Ess. 1998. Management considerations for small vernal pool preserves - the Phoenix vernal pools. pp. 250-254 in C. W. Witham, E. T. Bauder, D. Belk, W. R. Ferren Jrl, and R. Ornduff (eds). Ecology, conservation, management of vernal pool ecosystems - proceedings from a 1996 conference. California Native Plant Society, Sacramento, Ca. http://www.vernalpools.org/proceedings/roscoe.pdf.
DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488/
Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


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

Becoming more common in Central Valley vernal pools.


Sources of information:

DiTomaso, observational.
Carol Witham, vernal pool biologist, California Native Plant Society (Sacramento) and www.vernalpools.org. Personal observations.


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter No
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 No
Viable seed produced with both self-pollination and cross-pollination No
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 4
Total unknowns: 0
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 prairie
valley and foothill grassland
Great Basin grassland
vernal poolC, 5% - 20%
meadow and seepD, < 5%
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodlandD, < 5%
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): B
Distribution (highest score): C

Infested Jepson Regions

Click here for a map of Jepson regions

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