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.

Rating: Moderate

Cal-IPC Resources

  • 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.
  • CalWeedMapper - Statewide maps, climate models, and reports.
  • Cal-IPC News - Our quarterly newsletter. Each issue is available as a pdf.
  • Cal-IPC Symposium Proceedings - Presentations and papers from our annual Symposium.
  • Don't Plant a Pest! - Select your region to find non-invasive alternatives to ornamental species. Also see our statewide brochure on trees.

Other Resources

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.

Cal-IPC News Articles

  • None for this species.