IPCW Plant Report


Delairea odorata
Scientific name
Delairea odorata
Additional name information: Lemaire
Common name German ivy
Synonymous scientific names Senecio mikanioides
Closely related California natives 36
Closely related California non-natives: 5
Listed CalEPPC List A-1,CDFA nl
By: Carla Bossard


Distinctive features:
Cape ivy (Delairea odorata) is a
perennial vine with shiny, five- to six-pointed leaves, usually with two small
stipule-like lobes. There is one leaf at each node. Foliage is green to
yellow-green and has a distinct odor. Plants have extensive waxy stolons running
above and below ground. Below-ground stems are purple. Each flower is a yellow,
round discoid head the size of a dime. Flowers are arranged in groups of twenty
or more.


Asteraceae. Long-lived, branching, glabrous perennial vine with shiny stolons covered by thick cuticle. Climbs over other vegetation and foliage; grows to 30 in (89 cm) deep on the ground. Underground stolons purple-mottled and root adventitiously at nodes. Leaves: evenly spaced, with shiny cuticle; blades 1.2-3.2 in (3-8 cm), +/- petiole (often with two stipule-like lobes at base) +/- round; blades sharply, palmately 5-9 lobed. Inflorescence: heads discoid, 20-40; main phyllaries +/- 8, 0.12-0.16 in (3-4 mm), tips green; flowers: 0 ray flowers,


WHERE WOULD I FIND IT? Cape ivy is invasive in Italy (Catalano et
al. 1996), Australia (Fagg 1989), and the eastern United States, and currently
occupies more than 500,000 acres in California (Grotkopf, pers. comm. 1998,
Robison unpubl. data). It exists in many coastal forests the length of
California, with populations found from Del Norte County in northern California
to Canyons inland from San Diego. Typically found below 660 feet (


WHERE DID IT COME FROM AND HOW IS IT SPREAD? Cape ivy is native to moist mountain
forests of South Africa, where it has a limited natural range. Introduced in the
1850s as an ornamental in the eastern United States and to California by the
1950s (Elliot 1994), by the 1960s it had naturalized in Golden Gate Park, San
Francisco, and Marin County (Archbald 1995, Howell 1970). It spreads
vegetatively by stolons and fragmentation of stolons. Ninety-five percent of
fragments of green stolons containing only one node establish, and drying stolon
fragments in full sun for ten weeks does not stop them from rooting (Bossard
unpubl. data).


WHAT PROBLEMS DOES IT CAUSE? Cape ivy climbs over most other vegetation, forming a solid
cover that blocks light and smothers other vegetation. The weight of the ivy
mass sometimes causes trees to fall. Habitat for both plants and animals in
protected natural reserves has been rendered worthless when large portions are
occupied almost exclusively by cape ivy. Even in areas that have not become
monospecific, native plant species richness can be reduced about 50 percent,
with greater impact on annual than on woody perennial species (Alverez 1996). In
the same study, native species seedling richness decreased 75 to 95 percent in
areas containing cape ivy.

Cape ivy contains pyrrolizidine alkaloids (Stelljes et al. 1991)
and xanthones (Catalano et al. 1996) that make it unsuitable forage for most
fauna. Pyrrolizidine alkaloids such as retronecine, found in cape ivy foliage
and flowers, are known to be toxic to mammals and to spiders. Initial
experiments indicate that cape ivy foliage contains compounds that decrease fish
survival (Bossard 1998).

Flood control function along streams is impacted by cape ivy
infestations (Archbald 1995). Due to its shallow root system, cape ivy can
contribute to serious soil erosion problems on hillsides (Cudney and Hodel


HOW DOES IT GROW AND REPRODUCE? Cape ivy apparently reproduces only vegetatively in California. In Australia and in its native South Africa it reproduces by seed as well, which results from homogamous, radiate, self-incompatible flowers. Cape ivy flowers extensively in California, but evidently forms non-viable seeds. There have been occasional reports of ‰ÛÏseedlings‰Û from several populations of cape ivy in California. However, when thousands of seeds from twenty-six populations throughout California were examined by O‰ÛªConnell and Bossard in 1994, not one embryo-bearing, germinable seed was found (Bossard unpubl. data). It is possible the naturalized cape ivy in California is derived from a single genetic stock and, since this species is self-incompatible, California populations do not produce viable seed.

The period of most rapid vegetative growth is February to June, with some dieback occurring during July to October in areas without a constant water source (Bossard and Benefield 1995). After flowering and a month or two of rapid vegetative growth, this vine starts storing sugars from photosynthesis as starch in underground storage organs.

(click on photos to view larger image)



It flowers December to February. An
experiment in Golden Gate Park (Alverez 1995) indicates that a single patch of
cape ivy responds to resource changes more like an individual plant than a
colony of individuals, allocating resources to developing regions or regions
with decreasing resources from neighboring modules.


HOW CAN I GET RID OF IT? Cape ivy is difficult to eliminate for two
reasons: stolons and underground parts readily fragment while being removed, and
plants will grow from almost any remaining fragment. The most effective control
technique depends on the site topography, proximity of water, type of non-target
vegetation on the site, age and size of the infestation, importance of impacts
to non-target species, and type and quantity of resources available for control
efforts. All methods require appropriate timing, and possibly supplemental
revegetation by desirable species.

It is necessary to monitor removal sites every two months the
first year and every four months the second year to locate and kill resprouts.
Location and retreatment of resprouts is imperative or in six to eight months
the ivy can reinfest the whole area from which it was removed. After the second
year the site should be examined yearly to check for newly establishing
populations. This is particularly important if a stream is present or if
seasonal flooding occurs. Immediate removal of small new populations saves many
hours of removal efforts a few months later and prevents further spread to other
sites by fragmentation.


Physical control: Manual removal has been attempted, sometimes successfully, in
Volunteer Canyon, Marin County, Golden Gate National Recreation Area, San
Francisco, and in parks in the Santa Cruz area. Manual removal requires clearing
away native and invasive plant material to gain visual and physical access to
locations with cape ivy stems emerging from the ground. Roots and stems must be
teased out of the ground using a pointed or three-pronged mini-rake to loosen
the soil. At some sites, where cape ivy is growing mat-like on the ground, it
has been possible to roll up the entire infestation like a carpet using a potato
hoe or rake (Archbald 1995). In Marin County volunteers were able to clear an
average of 13.6 square meters of cape ivy per hour (Blumin and Peterson 1997).
Removed cape ivy should be placed in or on plastic and, if feasible, removed
from the area. Putting soda lime into cape ivy container bags will hasten the
otherwise slow breakdown of this plant material. Manual control is sometimes
followed with spot chemical treatment of resprouts.

Cape ivy tissues should not be put through a chipper or sent
unbagged to a dump site. Both would likely result in spread of cape ivy.
Returning at four- to eight-week intervals is necessary to locate and remove
overlooked and resprouting plants. Manual removal is labor-intensive but can be
accomplished where chemical applications cannot be used. The amount of
disturbance to non-target species varies with the type of vegetative community
infested, but it can result in increased erosion or in colonization by other
invasive plants. Supplemental revegetation needs should be considered on a
site-by-site basis.

Prescribed burning: This has not yet been attempted on cape ivy
because of the high moisture content of its foliage.


Biological control: Insects and fungi: An initial assessment of
potential biocontrol agents for cape ivy conducted in South Africa suggests that
there are seven promising insect candidates, including moth and beetle larvae
and root-, stem-, and seed-feeding insects (Grobbelaar et al. 1999). Led by
CalEPPC, an effort is underway to raise funds to continue to support the efforts
of the USDA Albany lab in developing biocontrol agents for cape ivy. Some of the
more promising insects are being tested in South Africa.


Chemical control: A mixture of foliar-sprayed 0.5 percent glyphosate (as Roundupå¨)
+ 0.5 percent triclopyr (as Garlon 4å¨) + 0.1 percent silicone surfactant (as
Silwitå¨) in water, applied as a foliar spray at 6.4 liters/ha proved effective
in killing even long-established and extensive infestations of cape ivy in two
applications, one year apart, in Golden Gate Park, San Francisco, and in a
second test of this method near Morro Bay. Applications must be done in late
spring when the plant is photosynthesizing actively but is past flowering, so
the active ingredients move down with the sugars that are transported to
underground storage organs. This mixture has a low concentration of active
ingredients, which results in a slow, progressively deadly impact on dense cape
ivy infestations with no measurable damage to non-target species (Bossard and
Benefield 1995). Since the mixture contains a surfactant and triclopyr, it
should be used cautiously and only within the guidelines specified on the label,
especially where the water table is only a few inches below the surface or along
pond or stream banks.

In Australia, clopyralid, (sold in California as Translineå¨),
was used successfully in concentrations of 150 g/liter clopyralid at application
rates of 6-8 liters/ha to remove dense infestations of cape ivy using the rope
wick method of application. This was done in two applications a year apart.
Clopyralid substantially damaged non-target species in the Asteraceae,
Solonaceae, Urticaceae, and Bignoneaceae families, but no appreciable damage was
found on non-target species of other plant families (Fagg 1989). This herbicide
is more expensive but also more selective than most other herbicides.

Tests of glyphosate alone (as Rodeoå¨) and glyphosate + the
surfactant R-11 at concentrations of 4 lbs/acre were carried out. While initial
impact on above-ground foliage was high, extensive resprouting occurred from
underground parts (Bossard and Benefield 1995). The rapid death of above-ground
parts prevented translocation of the active ingredients to the roots and
underground stems.