Delairea odorata (vine, climber)

Ecology Distribution Management Info Impact Info References and Links Contacts

Taxonomic name: Delairea odorata (Lemaire) Synonyms: Senecio mikanioides (Otto ex Walp.), Senecio scandens (DC) Common names: African ivy (English), Cape ivy (English), capeivy (English), climbing groundsel (English), German ivy (English), Italian ivy (English), parlor ivy (English) Organism type: vine, climber Delairea odorata is a perennial, evergreen vine that is native to South Africa but has been introduced into California where it is highly invasive and has started to dominate habitats and displace native species. Also known as "Cape ivy" or "German ivy", the vine was introduced as an ornamental groundcover. It spreads prolifically by vegetative reproduction through stolons. Although its native range is fairly limited, Delairea odorata can tolerate a wide range of environmental and habitat conditions. Description Delairea odorata is a fleshy, perennial, evergreen vine that can grow up to six metres long (Starr et al. 2003). The stem and leaves are glabrous and green (Starr et al. 2003) with underground stolons a mottled purple colour (Bossard, undated). The leaves are alternate, broadly deltate to "ivy-shaped", with 5-7 shallow, but sharply pointed lobes (State of Victoria, Department of Natural Resources and Environment, 2001), 3-10cm long and 3-6cm wide, palmately veined with petioles 1.5-7cm long (Starr et al. 2003). A pair of kidney-shaped leaves present at the base of large leaves and may be absent on older vines (State of Victoria, Department of Natural Resources and Environment, 2001). Flowers are axillary or terminal cymes, with individual flowers yellow, disk corollas 4-5mm long arranged in clusters, ray flowers absent (Starr et al. 2003). The fruit is an achene about 2mm long, often with a pappus (Starr et al. 2003) and a "crown" of hairs (State of Victoria, Department of Natural Resources and Environment, 2001). Similar Species Hedera helix More Occurs in: coastland, lakes, natural forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands, water courses, wetlands Habitat description Cape ivy is tolerant of a wide range of habitats from natural forests, rainforests, scrub and shrublands, grasslands, riparian corridors, lake shores, coastland, forest margins, roadsides, and waste places (Balciunas, 2002; Starr et al. 2003). It can grow in full sun or in the shade (Starr et al. 2003) and establishes on xeric (dry) or meisic (moderate) moisture sites (Jacobi & Warshauer, undated). Elevation ranges from 500-2500 metres in Hawaii (Jacobi & Warshauer, undated) but typically it is found below 200 metres in coastal regions (Starr et al. 2003). It is commonly found in high pH soils characterized by high fertility (Baars et al. 1998) and has been known to establish on salt exposed bluffs (Starr et al. 2003). It is tolerant of drought and freezing (Alvarez & Cushman, 2002). Its growth pattern and climbing mechanism is scrambling and creeping, clinging to exposed branches of shrubs and young trees, establishing best in early successional forests (Baars et al. 1998). General impacts Cape ivy is an oppurtunistic and aggressively growing perennial vine that can form dense vegetative groundcover mats that can prevent seedling establishment of native forbs and grasses (Alvarez, 1997). The climbing nature of the plant allows it to access light resources higher in the canopy and can prevent forest stand regeneration by smothering trees (Bossard, undated). The weight of large masses of Cape ivy have been known to bring down trees (Bossard, undated). D. odorata also competes for other resources like soil nutrients and water (Alvarez & Cushman, 2002). The reduction in diversity also effects higher trophic level organisms like several sensitive species of insects and predator complexes that rely on these invertabrates for food (Starr et al. 2003). Cape ivy has several negative impacts on riparian communities, including increased soil erosion along watercourses due to its shallow root system not capable of holding loose soils together (Bossard, undated). Toxic pyrrolizidine alkaloids and xanthones are found within the plant that are toxic to humans, mammals, and in particularly aquatic organisms. Due to the toxic compounds in this plant it is not considered widely palatable to most species, reducing forage quality (Starr et al. 2003). The dense vegetation can also displace burrowing shorebirds, like little penguins (see Eudyptula minor in IUCN Red List of Threatened Species), by taking up available space used for nesting (Dann, undated). Uses Originally introduced as a landscape plant due to its rapid growth and easy propagation, cape ivy is not recommended for use as an ornamental because of its aggressive growth habit and tendency to dominate and outcompete native vegetation (Starr et al. 2003). The entire plant contains toxic compounds and should be regarded with caution (Starr et al. 2003). Geographical range Native range: South Africa (USDA-GRIN, 2007). Known introduced range: California, Oregon, Hawaii, Eastern United States, Australia, New Zealand, Italy, British Isles, Southern Europe, Northern Africa, Canary Islands, Azores, Federated States of Micronesia (USDA-GRIN, 2007; PIER, 2006; Bossard, undated). Management information Preventitive measures: Delairea odorata should not be used as a landscape plant or sold as an ornamental in nursery stock. Education of the public on the harmful effects the plant has on native habitats and species should be a priority (Starr et al. 2003). Monitoring and mapping infestations as they arise is also considered a priority as well as follow-up monitoring and control to make sure infested areas remain clean (Jacobi & Warshauer, undated). A Risk Assessment of Delairea odorata for Hawaii and other Pacific islands was prepared by Dr. Curtis Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service. The alien plant screening system is derived from Pheloung et al. (1999) with minor modifications for use in Pacific islands (Daehler et al. 2004). The result is a score of 14 and a recommendation of: "Likely to cause significant ecological or economic harm in Hawaii and on other Pacific Islands as determined by a high WRA score, which is based on published sources describing species biology and behaviour in Hawaii and/or other parts of the world." Please follow this link management information: Delairea odorata for detailed management information. Reproduction Cape ivy can reproduce vegetatively or through seed production. Vegetative reproduction can occur at any time when the nodes of the stem, stolon, or leaf petiole are in contact with the soil (Alvarez & Cushman, 2002). Small fragmented pieces can root easily and quickly (Starr et al. 2003). D. odorata can also reproduce by seed but it seems it only does so in South Africa and Australia; no viable seed is produced in species that have invaded the coasts of California (Bossard, undated). It is theorized that since the flowers of D. odorata are self-incompatible that only a few genetic lines have been introduced and therefore inhibit viable seed production (Bossard, undated). Lifecycle stages Delairea odorata has the most rapid vegetative growth between the months of February and June (Bossard, undated) and tends to dieback during dry periods when there is a lack of available water resources (Starr et al. 2003). The plant flowers between December and January in California (Alvarez & Cushman, 2002) and between July and September in Australia (State of Victoria, Department of Natural Resources and Environment, 2002). Non-viable or poor germinating seed is produced in California (Starr et al. 2003) so the main form of propagation is by vegetative means. However it has been noted by Nelson (1999) in Starr et al. (2003), that seed set and germination is enhanced by hard frosts, cool winters and rain. Principal sources: Starr, F., Starr, K., & Loope, L., Jan. 2003, Delairea odorata Cape ivy, United States Geological Survey, Biological Resources Division, Haleakala Field Station, Maui, Hawaii; Alvarez, M.E., 1997, Management of Cape-ivy (Delairea odorata) in the Golden Gate National Recreation Area, California Exotic Pest Plant Council, 1997 Symposium Proceedings, [online]; State of Victoria, Department of Natural Resources and Environment, Aug. 2001, Coastal Notes, Cape ivy, CW0008, ISSN 1329-4806. Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG) Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment To contribute information, please contact Shyama Pagad. Last Modified: Monday, 4 October 2010