Mentha pulegium

Mentha pulegium_pennyroyal JM Di Tomaso
Photo courtesy Joseph DiTomaso

Synonyms: Mentha daghestanica Boriss.; Pulegium dagestanicum (Boriss.) Holub; Pulegium vulagare Mill.

Common names: pennyroyal; European pennyroyal; grows-in-a-ditch

Mentha pulegium (pennyroyal) is a perennial mint (family Lamiaceae) with a variable habit, ranging from low-growing, spreading plants to lanky, upright sub-shrubs. Although considered uncommon in much of California, pennyroyal occurs in the Sierra foothills, Central Valley, and most coastal counties from the Mexican border to Oregon. It is common as an obligate wetland indicator species in seasonally inundated soils of valley bottomlands, usually below 1,640 feet (500 m) elevation. Pennyroyal grows in flooded or seasonally wet areas: seeps, streamsides, vernal pools and swales, marshes, and ditches. Although pennyroyal is considered moderately invasive in wetlands its ecological impacts are not well documented. It clearly prospers in habitats that were once dominated by native plants, suggesting that it may have displaced some species. In particular, the flora of vernal pools may have suffered loss of habitat through the introduction of pennyroyal.

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.

Cal-IPC Newsletter Articles

Cal-IPC Symposium Presentations

  • Connick, S. and M. Gerel (2004). Partnering to prevent invasions of plants of horticultural origin. California Invasive Plant Council Symposium 2004. Ventura, CA.
  • Pickart, A. J. and K. S. Wear (1999). The ecology of Parentucellia viscosa in dune wetlands. California Exotic Pest Plant Council Symposium '99. Sacramento, CA, California Exotic Pest Plant Council.
  • Quinn, L., B. Davis, et al. (2006). Does horse manure harbor invasive plants? Cal-IPC Symposium. Rohnert Park, CA.

Other Mentha pulegium Information

  • CalPhotos - Images of plants taken mostly in California.
  • CalFlora - Distribution information based on submitted observations and herbarium specimens.
  • 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.