Invasiveness Assessment - Cape ivy (Delairea odorata) in Victoria
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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.
| Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here. |
The following table provides information on the invasiveness of Cape ivy.
A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:
Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1 MB)
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Common Name: Cape ivy
Scientific name: Delairea odorata
| Question | Comments | Rating | Confidence |
| Establishment | |||
| Germination requirements? | Germination is reported to be rare, occurring in autumn. However vegetative propagules (pieces of stem and stolons) which is the main form of reproduction can root and grow when conditions are suitable (Blood 2001) | H | MH |
| Establishment requirements? | Reported to invade rainforest (Carr, Yugovic and Robinson 1992). Therefore can establish under low light conditions. Cut stems can survive months, then set root and grow when exposed to suitable conditions (Blood 2001). Therefore has some requirement for establishment. | MH | MH |
| How much disturbance is required? | Establishes in undisturbed /minor disturbed natural ecosystems: heath land: sclerophyll forest and woodland: riparian vegetation: rainforest (Carr, Yugovic and Robinson 1992). | H | MH |
| Growth/Competitive | |||
| Life form? | Vine (Carr, Yugovic and Robinson 1992). | ML | MH |
| Allelopathic properties? | No allelopathic properties described. However the species does contain pyrrolizidine alkaloids and xanthones, which are known to be toxic to fauna but not flora (Bossard, Randell & Hoshovsky 2000). | L | M |
| Tolerates herb pressure? | Contains pyrrolizidine alkaloids and xanthones that make it unsuitable forage for most fauna and if slashed to ground level plants can regrow from rootstock (Bossard, Randell & Hoshovsky 2000). Bio-Control agents have been researched in Sth Africa and a program developed in California, however no such efforts are reported in Australia (Bossard, Randell & Hoshovsky 2000 and Balciunas & Smith 2006). | H | MH |
| Normal growth rate? | Reported to be a fast growing vine (Weber 2003). In California it has been reported as spreading more rapidly than any other weeds species. Average growth rates of plants around San Francisco have been calculated to one foot of growth per month. (Alvarez 1997). | H | MH |
| Stress tolerance to frost, drought, w/logg, sal. etc? | Tolerates some salinity (recorded on salt exposed bluffs) (Alvarez 1997). Drought tolerant (Blood 2001). Reported in seasonal wetlands, therefore tolerant of waterlogging (Bossard, Randell & Hoshovsky 2000). Frost tender (Blood 2001), however Nelson (1999) reports that hard frosts appear to stimulate seed set, therefore while frost may damage the plant, it may not kill it. Foliage has high moisture content and therefore resistant to burning also plants can regrow from rootstock (Bossard, Randell & Hoshovsky 2000). | H | MH |
| Reproduction | |||
| Reproductive system | Produces seed, however primary mode of reproduction is vegetative, through stolons and stem fragments (Bossard, Randell & Hoshovsky 2000 and Muyt 2001). | H | MH |
| Number of propagules produced? | Large plants can produce more than 40,000 seeds annually (Muyt 2001). | H | MH |
| Propagule longevity? | Reproduction primarily through vegetative means .Stem fragments can persists for months before setting root under favourable conditions (Blood 2001). Seed longevity unknown. Seed doesn’t germinate readily and the seeds are tiny, 2 mm long (Muyt 2001). Therefore assume propagule longevity <5yrs | L | M |
| Reproductive period? | Long lived, can form monocultures (Bossard, Randell & Hoshovsky 2000). | H | MH |
| Time to reproductive maturity? | Reach sexual maturity within two years (Muyt 2001) | MH | MH |
| Dispersal | |||
| Number of mechanisms? | Seeds are 2 mm with hairs attached, spread by wind and water (Muyt 2001). Vegetative propagules spread by water and deliberate human actions (Alvarez 1997). | H | MH |
| How far do they disperse? | Wind dispersed seed can travel distances of more than 1 km. | H | MH |
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