Plant Assessment Form

Helichrysum petiolare

Common Names: licorice plant

Evaluated on: 5/22/03

List committee review date: 06/06/2003

Re-evaluation date:


Joe DiTomaso
UC Davis
Weed Science Program, Robbins Hall, Univ. California, Davis CA 95616

List commitee members

Joe DiTomaso
Peter Warner
Alison Stanton
Carla Bossard
Cynthia Roye
Jake Sigg
Doug Johnson
Brianna Richardson

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Reviewed Scientific Publication
Four-part score UCUD Total Score
1.2 ?Impact on plant community C. Minor Observational
1.3 ?Impact on higher trophic levels U. Unknown
1.4 ?Impact on genetic integrity D. None Observational
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Other Published Material
Total Points
13 Total Score B
2.2 ?Local rate of spread with no management B. Increases less rapidly Observational
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Other Published Material
2.5 ?Potential for human-caused dispersal A. High Other Published Material
2.6 ? Potential for natural long-distance dispersal D. None Other Published Material
2.7 ?Other regions invaded U. Unknown
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Other Published Material
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Other Published Material

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:

Unknown Not studied.

Sources of information:

Question 1.2 Impact on plant community composition,
structure, and interactions?
C Observational
Identify type of impact or alteration:

Appears to displace native shrubs in heavily infested areas. Can occupy about 10-25% of the cover in heavy infested area.

Sources of information:


Question 1.3 Impact on higher trophic levels? U
Identify type of impact or alteration:


Sources of information:

Question 1.4 Impact on genetic integrity? D Observational

Probably none. No known native species within the genus Helichrysum in California.

Sources of information:


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

Appears in coastal shrub areas in absence of human activity and even in sites inaccessible to most humans.

Sources of information:

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

Has been naturalized for at least 35 years. Appears to be increasing, but may not be doubling <10 years. Reported in Marin Flora in 1969 and in the Mendocino flora in 1990.

Sources of information:


Question 2.3 Recent trend in total area infested within state? B Observational
Describe trend:

Same as applied to 2.2. Since populations are still localized and left uncontrolled, it is likely that it is not doubling in <10 years.

Sources of information:


Question 2.4 Innate reproductive potential? A Other Published Material
Describe key reproductive characteristics:

Produces seed and reproduces vegetatively by fragmentation of stems. Plants are brittle and break off easily. Stem fragments can root at nodes.

Sources of information:

Question 2.5 Potential for human-caused dispersal? A Other Published Material
Identify dispersal mechanisms:

Still sold by nursery industry and can move throughout coastal areas this way. Long distance movement by landscapers and subsequent short distance movement by seeds and vegetative fragments.

Sources of information:

Sigg, J. 1997. CalEPPC News 5(1):8; Observational-DiTomaso

Question 2.6 Potential for natural long-distance dispersal? D Other Published Material
Identify dispersal mechanisms:

Seeds not reported to disperse long distances with wind. Fragments probably remain localized unless dispersed by animals, but this is unknown.

Sources of information:

Question 2.7 Other regions invaded? U
Identify other regions:


Sources of information:

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

Coastal shrub areas in Marin County most commonly invaded. Occasionally found on coastal bluff scrub in North Coast. Reported in coastal mixed conifer forests in Monterey County (Del Monte Forest). Introduced as an ornamental in the 1960s. Expected to invade coastal grasslands but no current reports.

Sources of information:

Sigg, J.2000. In, Invasive Plants of Californias Wildlands. CalEPPC. UC Press, Berkeley

Question 3.2 Distribution/Peak frequency? D Other Published Material
Describe distribution:

heavy infestation in localized areas, but not widespread yet, even in that community type. Largest infestation in Stinson Beach, CA.

Sources of information:


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Unknown
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 Unknown
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 No
Fragments easily and fragments can become established elsewhere Yes
Resprouts readily when cut, grazed, or burned Yes
Total points: 6
Total unknowns: 4
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, reservoirs
Aquatic Systemsrivers, streams, canals
Scrub and Chaparralcoastal bluff scrubD, < 5%
coastal scrubD, < 5%
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forestD, < 5%
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): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Central West
  • Great Valley
  • Northwest
  • Southwest