Phalaris aquatica

Phalaris aquatica_hardinggrass_ JM Di Tomaso
Photo courtesy Joseph DiTomaso

Synonyms: Phalaris commutata, Phalaris stenoptera, Phalaris tuberosa

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

Phalaris aquatica (hardinggrass) is a perennial grass (family Poaceae) found throughout California. Hardinggrass is widespread in California because it has been used as a forage species and for revegetating after fires. It is most common in coastal valley and foothill grasslands from Oregon to the Mexican border. It is also found in the Sacramento and San Joaquin valleys at elevations below 4,000 feet (1,200 m). Hardinggrass is typically found along roadsides that are seldom mowed, allowing this tall, erect, leafy plant to dominate neighboring vegetation. In wildland habitats, hardinggrass can out-compete and displace native plant species. Tall stands of its dry foliage can present a fire hazard in summer.

Cal-IPC Rating: Moderate

Cal-IPC Assessment

Plant Assessment Form - Information gathered by Cal-IPC on the impacts, rate of spread, and distribution of invasive plants in California. Does not include management information.

Weed RIC Management Notes

  • Management Notes - Information on management techniques and effectiveness from the University of California Cooperative Extension’s Weed Research & Information Center.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

  • Alvarez, M., C. Colson, et al. (2008). Results from the use of a novel method, HydroMechanical Obliteration, at the Golden Gate National Recreation Area in west Marin. California Invasive Plant Council Symposium 2008. Chico, CA, California Invasive Plant Council Symposium 2008.
  • Samuels, S., L. Julian, et al. (2008). Controlling an invasive grass in a grassland setting - Harding grass control in the Bald Hills of Redwood National and State Parks. California Invasive Plant Council Symposium 2008. Chico, CA, California Invasive Plant Council.
  • Antonio, C. D. and J. Gerlach (2003). Annual grasses: Status of biology and control. California Invasive Plant Council Symposium 2003. Kings Beach, CA.
  • Clines, J., J. DiTomaso, et al. (2004). Grasses working group. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Corbin, J. D., M. Thomsen, et al. (2004). Out of the frying pan: Invasion of exotic perennial grasses in coastal prairies. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Stafford, M., S. Farrell, et al. (2006). Control of Phalaris aquatica on lowland coastal terrace prairie in Richmond, CA. Cal-IPC Symposium. Rohnert Park, CA.
  • Thomsen, C. D., W. A. Williams, et al. (1996). Yellow starthistle management with grazing, mowing, and competitive plantings. California Exotic Pest Plant Council Symposium '96. San Diego, CA.

Other Phalaris aquatica Information

  • CalPhotos - Images of plants taken mostly in California.
  • Calflora - See the distribution of this species on Calflora's map of California.
  • CalWeedMapper - Distribution information with ability to determine regional priorities.
  • Jepson Online Interchange for California Flora - Information on taxonomy, biology, and distribution from UC Berkeley's Jepson Herbarium.
  • USDA PLANTS Database - Federal database with information on identification and distribution, and links to websites in individual states.
  • Bugwood - National database from the Center for Invasive Species and Ecosystem Health at the University of Georgia.