Plant Assessment Form

Phalaris aquatica

Synonyms: Phalaris commutata, Phalaris stenoptera, Phalaris tuberosa

Common Names: harding grass; bulbous canarygrass; phalaris; toowoomba grass

Evaluated on: 4/5/05

List committee review date: 08/07/2005

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
Joseph DiTomaso
University of California-Davis
Dept. Plant Sci., Mail Stop 4, Davis, CA 95616
530-754-8715
jmditomaso@ucdavis.edu

List commitee members

Carla Bossard
John Randall
Carri Pirosko
Dan Gluesenkamp
Gina Skurka
Brianna Richardson

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes B Other Published Material
Impact?
Four-part score BABU Total Score
B
1.2 ?Impact on plant community A. Severe Other Published Material
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 B. Moderate Other Published Material
Invasiveness?
Total Points
14 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)
A. High Other Published Material
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal B. Occasional Other Published Material
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Other Published Material
Distribution?
Total Score B
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? B Other Published Material
Identify ecosystem processes impacted:

Water availability (competing with other plants). Defoliation of phalaris reduced loss of water from the topsoil.


Sources of information:

Dear, B. S., P. S. Cocks, E. C. Wolfe, and D. P. Collins. 1998. Established perennial grasses reduce the growth of emerging subterranean clover seedlings through competition for water, light, and nutrients. Australian Journal of Agricultural Research. 49:41-51
Dan Gluesenkamp, Audubon Canyon Ranch, pers. obs.


Question 1.2 Impact on plant community composition,
structure, and interactions?
A Other Published Material
Identify type of impact or alteration:

Seedlings compete poorly with established vegetation, but larger plants easily displace native vegetation (1, 2). Can form localized dense stands (3, 4, 5).


Sources of information:

1. DiTomaso, J.M., and E. H. Healy. 2003. Aquatic and Riparian Weeds of the West. University of California, Agriculture and Natural Resources Publication 3421.
2. Dear, B. S., P. S. Cocks, E. C. Wolfe, and D. P. Collins. 1998. Established perennial grasses reduce the growth of emerging subterranean clover seedlings through competition for water, light, and nutrients. Australian Journal of Agricultural Research. 49:41-51
3. Peterson, D. L. 1988. Element stewardship abstract for Phalaris tuberosa (harding grass). The Nature Conservancy, Arlington, VA. Available: tncweeds.ucdavis.edu/esadocs/phalaqua.html
4. Dan Gluesenkamp, Audubon Canyon Ranch, pers. obs.
5. Brianna Richardson, Acterra, pers. obs.


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

Planted for forage but can be toxic to animals when consumed in large quantities. Causes a neurological condition called "phalaris staggers" or heart failure.


Sources of information:

DiTomaso, J.M., and E. H. Healy. 2003.


Question 1.4 Impact on genetic integrity? U

There are four native species of Phalaris, but we have 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:

Seedlings are easily outcompeted by established vegetation.


Sources of information:

DiTomaso, J.M., and E. H. Healy. 2003.


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

In some areas spread can be rapid and in other areas more slowly.


Sources of information:

DiTomaso, observational


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

Spreading


Sources of information:

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

Perennial grass. Reproduces by seed. Becomes dormant during summer in dry areas (1). Can also spread by rhizomes (2), but not as strongly as reed canary grass (3). Grazing decreases abundance of phalaris (2). Seed production varies with plant density, soil type, and weather conditions, but some plants can produce 40,000 seeds per square m. Seeds produced between May and September (3)


Sources of information:

1. DiTomaso, J.M., and E. H. Healy. 2003.
2. Leiva, M. J., and R. F. Ales. 2000. Effect of grazing on the population biology of Phalaris aquatica. Journal of Range Management. 53:277-281
3. Harrington, K.C., and W. T. Lanini. 2000.


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

Was introduced to provide forage on pastures and rangeland. Has escaped cultivation in riparian areas and other moist places. Seeds can be dispersed by human activities (1). Seeds also sold over the internet to produce grass harvestable for hallucinogenic drugs (2).


Sources of information:

DiTomaso, J.M., and E. H. Healy. 2003.
Information on Phalaris aquatica. http://peyote.com/jonstef/phalaris.htm, and other websites


Question 2.6 Potential for natural long-distance dispersal? B Other Published Material
Identify dispersal mechanisms:

Seeds can be dispersed with animals, but this is mostly short distance. Near aquatic areas the seed can move greater distances.


Sources of information:

DiTomaso, J.M., and E. H. Healy. 2003. Aquatic and Riparian Weeds of the West. University of California, Agriculture and Natural Resources Publication 3421.
Harrington, K.C., and W. T. Lanini. 2000.


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

Native to Mediterranean Europe but the cultivar in California was introduced from Australia. Also has escaped cultivation in Arizona, Oregon and a few states in the southern and eastern US


Sources of information:

1. DiTomaso, J.M., and E. H. Healy. 2003.
2. Harrington, K.C., and W. T. Lanini. 2000.


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

Inhabits riparian and other moist areas. A facultative wetland species. Tolerates frost and drought. Present in northwestern California., central Sierra Nevada, Central Coast, and South Coast to 1200m (1). Common in coastal valleys and foothill grasslands from Oregon to the Mexican border. Also found in the Sacramento and San Joaquin Valleys. Typically found along roadsides that are seldom defoliated (2).


Sources of information:

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

Mainly found along roadsides and not as common in wildland areas.


Sources of information:

DiTomaso, observational


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 Yes
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 Yes
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned Yes
Total points: 7
Total unknowns: 2
Total score: A?

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 scrubD, < 5%
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 pool
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 woodlandD, < 5%
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): A
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

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