Phalaris aquatica

Phalaris aquatica_hardinggrass_ JM Di Tomaso
Photo: Joseph DiTomaso

Synonyms: Phalaris commutata, Phalaris stenoptera, Phalaris tuberosa

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

Phalaris aquatica (harding grass) is a perennial grass (family Poaceae) found throughout California. Harding grass 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). Harding grass is typically found along roadsides that are seldom mowed, allowing this tall, erect, leafy plant to dominate neighboring vegetation. In wildland habitats, harding grass 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?

CDFA Rating: None?


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 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

Presentations are linked where available. Where a presentation is not available, find more information by reading the abstract in the Cal-IPC Symposia Archive.

Other Phalaris aquatica Information

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

    Phalaris aquatica_florets_copyright2008_NealKramer
    Phalaris aquatica (harding grass) florets. Photo: &#169 2008 Neal Kramer
    Phalaris aquatica_inflorescence_copyright2008_NealKramer
    Phalaris aquatica (harding grass) inflorescence. Photo: &#169 2008 Neal Kramer
    Phalaris aquatica_leaf blade and sheath_copyright2008_NealKramer
    Phalaris aquatica (harding grass) leaf blade and sheath. Photo: &#169 2008 Neal Kramer
    Phalaris aquatica (harding grass) infestation. Photo: Ron Vanderhoff