Plant Assessment Form

Delairea odorata

Synonyms: Senecio mikanioides

Common Names: Cape-ivy; German ivy; Italian ivy; ivy groundsel; parlor ivy; water ivy

Evaluated on: 12/29/04

List committee review date: 11/03/2005

Re-evaluation date:


Gina Skurka, Agricultural Technician
California Department of Food and Agriculture
1220 N Street, Room A-357, Sacramento, CA 95814
(916) 654-0768
Elizabeth Brusati, project manager
California Invasive Plant Council
1442-A Walnut St. #462, Berkeley, CA 94709

List committee members

Joe DiTomaso
John Randall
Carla Bossard

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? High
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes A. Severe Other Published Material
Four-part score AAAD Total Score
1.2 ?Impact on plant community A. Severe Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels A. Severe Other Published Material
1.4 ?Impact on genetic integrity D. None Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Other Published Material
Total Points
19 Total Score A
2.2 ?Local rate of spread with no management A. Increases rapidly Other Published Material
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
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal A. Frequent Other Published Material
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
Total Score B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. Low Reviewed Scientific Publication

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? A Other Published Material
Identify ecosystem processes impacted:

Dense canopy blocks sunlight from reaching plants underneath. Contains potent alkaloids including pyrrolizidine, which can be leached into water. Due to its shallow root system, cape ivy can contriubte to serious soil erosion problems on hillsides. Flood control function along streems is impacted by infestations Severe or moderate alteration of ecosystem processes. Decreases light availability and releases toxins into the water.

Sources of information:

Question 1.2 Impact on plant community composition,
structure, and interactions?
A Reviewed Scientific Publication
Identify type of impact or alteration:

Associated with reductions in the species richness and diversity of both native and nonnative species. Abundance of native and nonnative seedlings were each significantly lower in plots invaded by Cape ivy compared to uninvaded plots. It grows rapidly and forms a thick blanket, which not only covers and smothers the other vegetation on the ground, but it clambers over small shrubs, and up trees and other vertical objects to a height of eight meters, frequently killing these as well. Formation of stands dominated (>75% cover) by this species. Severe alteration of plant community composition and structure.

Sources of information:

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

Eleven different pyrrolizidine alkaloids, which are potent mammalian hepato-toxins, have been detected in Cape ivy and some of these are consumed and sequestered by migrating monarch butterflies. When dipped into an aquarium, Cape ivy will kill fish and a variety of aquatic insects. Refuges created as reserves for native animal and plant species are rendered worthless when large portions of their acreage are occupied by Cape ivy. Underlying vegetation and pre-invasion microclimates are obliterated. Additional Golden Gate National Recreation Area vegetation communities infested with Cape ivy support two federally endangered butterflies, federally threatened coho salmon and steelhead, and federal endangered freshwater shrimp. Cape ivy's occurrence in habitats used by these species may have some detrimental effects on their declining populations. Endangerment of existing native species/population. Severe/moderate alteration of higher trophic populations.

Sources of information:

Balciunas, J, E. Grobbelaar, R. Robison, and S. Neser. Distribution of Cape ivy (Delairea odorata), a growing threat to western riparian ecosystems. For publication in J. Aquatic Plant Management.
Archbald, G. (1995) Biology and Control of German Ivy: An Update for California Department of Fish & Game, Pesticide Applicators Seminar.
DiTomaso, J. and E. Healy. Weeds of California and Other Western States, (Unpublished).
Robison, R. (2000) Distribution, Reproductive Dynamics and Physiology of Cape ivy (Delairea odorata syn Senecio mikanioides), an Invasive Wildland Weed of the Pacific Coast (Unpublished).

Question 1.4 Impact on genetic integrity? D Other Published Material

Cape ivy is not known to reproduce readily by seed in North America; however, viable seed was found in California. No known hybridization.

Sources of information:

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

Takes over habitats regardless of anthropogenic or natural disturbance. Cape ivy on the west coast prefers and grows vigorously in physically challenging environments such as streamside thickets, willows and poison oak. Severe invasive potential. This species can establish independent of natural or anthropogenic disturbance.

Sources of information:

Archbald, G and J. Sigg. (1998) A Modified Proposal for Biocontrol of Cape Ivy.

Question 2.2 Local rate of spread with no management? A Other Published Material
Describe rate of spread:

Cape ivy spread in the Marin headlands from 8.8 acres in 1987 to 67.3 acres in 1996 (765% in 9 years). A 1987 survey in a portion of the Golden Gate National Recreation Area located 3.6 hectares of Cape ivy, which when resurveyed 9 years later, had expanded nearly nine-fold to 27.2 hectares. Increases rapidly, doubling in less than 10 years.

Sources of information:

Nelson, D. 1999. Cape Ivy, Another Problem Plant for the Ventana Wilderness. The Double Cone Quarterly. Spring Equinox 1999, Vol II, No I, <<>>.
Balciunas, J, E. Grobbelaar, R. Robison, and S. Neser. Distribution of Cape ivy (Delairea odorata), a growing threat to western riparian ecosystems. For publication in J. Aquatic Plant Management.

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

D. odorata ranges along the entire California coast and some mesic areas of the Central Valley. Over 500,000 acres are infested in California, and on Catalina Island, 13 populations were detected with 6 in riparian habitats and 1 in island scrub oak chaparral near a riparian area. All populations were small with sparse cover. Many of the plants were less than 2 feet long, indicating new establishment. D. odorata has been targeted for control at the Catalina Island Conservancy, Marin Headlands, Golden Gate National Park, Parks within Santa Cruz County, Dos Palmas Reserve, Lake Mead National Recreational Area, Elkhorn Slough National Estuarine Research Reserve, Big Sur and San Luis Creek and San Simeon in San Luis Obispo. It can tolerate both freezing and drought, indicating a wide range of climatic preferences. On Catalina Island, 13 populations were recorded in 2003 totalling 13,825 square feet.

Sources of information:

Question 2.4 Innate reproductive potential? A
Describe key reproductive characteristics:

Cape ivy spreads primarily by vegetative means, breaks apart easily and both stem nodes and leaf petioles are capable of rooting. Insect-pollinated. Reproduces vegetatively from rhizomes, stolons, and fragments of rhizomes, stolons and stems and in some locations, by seed. While most seeds produced are not viable, some viable seeds develop in most sites throughout California and Oregon
D. odorata is a perennial that reproduces mainly by the proliferation of stolons in California, but produces viable seed in its native range and areas invaded in Australia; however, untill recently in California no viable seed was thought to be produced. Flowering occurs extensively during December to February, and the flowers are self-incompatible. 95% of all stolons containing only 1 node establish. Rapid vegetative regrowth occurs between February and June. Drying stolons in the sun for ten weeks does not inhibit their ability to root. .

Sources of information:

Nelson, D. 1999. Cape Ivy, Another Problem Plant for the Ventana Wilderness. The Double Cone Quarterly. Spring Equinox 1999, Vol II, No I, <<>>.
DiTomaso, J. and E. Healy. Weeds of California and Other Western States, (Unpublished).
Robison, R. E-mail communication. 1/4/2005.
Balciunas, J. 2001. Viable seed production by cape ivy in California finally confirmed. CalEPPC News 9(2): 13.

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

Cape ivy is being sold as an ornamental in North America. Fragments as short as one half inch, carried by runoff or landscape machinery, can take root and colonize new areas. Listed in Sunset Western Garden Book.

Sources of information:

Balciunas, J, E. Grobbelaar, R. Robison, and S. Neser. Distribution of Cape ivy (Delairea odorata), a growing threat to western riparian ecosystems. For publication in J. Aquatic Plant Management.
Alvarez, M. (1997) Management of Cape-ivy (Delairea odorata) in the Golden Gate National Recreation Area. CalEPPC 1997 Symposium Proceedings.
Found in Cal-IPC nursery survey 2004.
Brenzel, K. N. 2001. Sunset Western Garden Book. Sunset Publishing Company, Menlo Park, CA

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

Seeds disperse with wind, water, and soil movement. If there is a Cape ivy source upstream, high water flows in the winter can be expected to transport pieces of plants down-stream, which can begin new colonies. Occasional long distance dispersal by animals or abiotic mechanisms.

Sources of information:

Moore, K. (1997) Battling the Kudzu of the West: Controlling Cape Ivy (formerly German ivy) by Hand Removal. CalEPPC News, Fall 1997, Page 4.

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

Also present in Oregon and Hawaii. Listed as a noxious weed in Australia. Present in Italy and Spain.

Sources of information:

USDA, NRCS. 2004. The PLANTS Database, Version 3.5 ( National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

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

D. odorata was first introduced to the North American east coast in the 1850's, and Marin County and Golden Gate Park, California in the 1950's for landscaping. Within 10 years it became naturalized. In California, populations have been found in following communities: grasslands, open oak forests, coastal scrub, Monterey pine forests, coastal bluff, riparian forests, old growth forests, seasonal wetlands, dunes, serpentine soil, and exotic shrub and forest communities. Also grows under eucalyptus trees, unlike most other species (Bossard, pers. obs.)

Sources of information:

Bossard, C.C. 2000. Delairea odorata. Bossard, C.C., J.M. Randall, and M.C. Hoshovsky, (eds). Pp. 154-158. In, Invasive plants of Californias wildlands. Berkeley, California: University of California Press.
Elliot, W. 1994. German ivy engulfing riparian forests and heading for the uplands. CalEPPC News 2(1): 9.
Hamingson, E.E. and M.E. Alvarez. 2000. Assessing cape-ivy control in two California National Parks. P. 36 in: Kelley, M. (ed.). 2003. Proceedings of the California Exotic Pest Plant Council Symposium Vol. 6: 2000-2002.
Dudley, T. 1998. Exotic plant invasions in California riparian areas and wetlands. Fremontia 26(4): 24-29.
Freitzke, S. and P. Moore. 1998. Exotic plant management in National Parks of California. Fremontia 26(4):49-53.

Question 3.2 Distribution/Peak frequency? C Reviewed Scientific Publication
Describe distribution:

see 3.1

Sources of information:

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter No
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination No
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: 6
Total unknowns: 0
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 prairieD, < 5%
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 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 forestD, < 5%
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): C

Infested Jepson Regions

Click here for a map of Jepson regions

  • Cascade Range
  • Central West
  • Great Valley
  • Northwest
  • Southwest