Plant Assessment Form

Mentha pulegium

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

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

Evaluated on: 7/31/03

List committee review date: 01/08/2003

Re-evaluation date:


Peter J. Warner
California Dept. of Parks and Recreation; CalEPPC
P. O. Box 603, Little River, CA 95456-0603
(707) 937-9172; (707) 937-2278

List commitee members

Jake Sigg
Peter Warner
Joe DiTomaso
Doug Johnson
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? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Four-part score UBCU Total Score
1.2 ?Impact on plant community B. Moderate Other Published Material
1.3 ?Impact on higher trophic levels C. Minor Other Published Material
1.4 ?Impact on genetic integrity U. Unknown
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Reviewed Scientific Publication
Total Points
18 Total Score A
2.2 ?Local rate of spread with no management A. Increases rapidly Observational
2.3 ?Recent trend in total area infested within state A. Increasing rapidly Other Published Material
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal A. High Reviewed Scientific Publication
2.6 ? Potential for natural long-distance dispersal B. Occasional Reviewed Scientific Publication
2.7 ?Other regions invaded B. Invades 1 or 2 ecological types Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Other Published Material
Total Score A
3.2 ?Distribution/Peak frequency
(see Worksheet C)
B. Moderate 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? U Reviewed Scientific Publication
Identify ecosystem processes impacted:

generally unknown, but could affect evapotranspiration rates from vernal pools and other wetland habitats inference based on losses of vernal pool species from pennyroyal-infest pools

Sources of information:

Peter Warner (personal observation)

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

displacement of native species; changes in community composition observations; inference from habitat information provided in print, both peer-reviewed and other

Sources of information:

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

potentially toxic to herbivores species known to be toxic to domestic livestock

Sources of information:

Question 1.4 Impact on genetic integrity? U

potential for hybridization with native taxon (M. arvensis) hybridization cited as common in published information

Sources of information:

Hickman, JC (editor). 1993. The Jepson Manual: Higher Vascular Plants of California. University of California Press, Berkeley.

Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
A Observational
Describe role of disturbance:

species invades most commonly in heavily grazed areas, compacted soils, roadside ditches, areas of sedimentation

Sources of information:

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

appears to spread rapidly into available wetland habitats, even those with substantial cover by other species

Sources of information:

Peter Warner (personal observations)

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

appears widespread already, but probably still expanding range of suitable habitats infested

Sources of information:

Question 2.4 Innate reproductive potential? A Reviewed Scientific Publication
Describe key reproductive characteristics:

seeds, stolons, rhizomes

Sources of information:

Question 2.5 Potential for human-caused dispersal? A Reviewed Scientific Publication
Identify dispersal mechanisms:

propagated, sold, planted horticulturally; vegetative propagules easily fragmented

Sources of information:

Question 2.6 Potential for natural long-distance dispersal? B Reviewed Scientific Publication
Identify dispersal mechanisms:

seeds, rhizomes, stolons attached to animals, humans

Sources of information:

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

Australian grazing lands (natural habitat?); potential for increase in range in CA

Sources of information:

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

widespread in cismontane wetlands (obligate wetlands indicator species); reported from over 30 counties in CA

Sources of information:

U. S. Fish and Wildlife Service website:; CalFlora database (

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

very common in N. Calif. coastal wetlands, especially disturbed sites

Sources of information:

Peter Warner (personal observations)

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 Yes
Resprouts readily when cut, grazed, or burned Yes
Total points: 9
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, reservoirsC, 5% - 20%
Aquatic Systemsrivers, streams, canalsD, < 5%
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparralC, 5% - 20%
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grasslandB, 20% - 50%
vernal poolC, 5% - 20%
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fenC, 5% - 20%
marsh and swampC, 5% - 20%
Riparian and Bottomland habitatriparian forestC, 5% - 20%
riparian woodlandD, < 5%
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
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): B

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