Delairea odorata (Cape ivy)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Hosts/Species Affected
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Plant Trade
- Impact Summary
- Environmental Impact
- Impact: Biodiversity
- Threatened Species
- Social Impact
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Delairea odorata Lemaire
Preferred Common Name
- Cape ivy
Other Scientific Names
- Senecio mikanioides Harvey
- Senecio mikanioides Harvey ex Otto
- Senecio mikanioides Otto ex Walp.
Local Common Names
- Australia: ivy groundsel
- Germany: Greiskraut, Efeu-
- New Zealand: German ivy
- USA: German ivy; parlor ivy
- USA/Hawaii: Italian ivy
- SENMI (Senecio mikanioides)
Summary of InvasivenessTop of page D. odorata has demonstrated its invasive nature on three continents, with California, USA and parts of Australia probably being the worst impacted by this South African vine. In California, it has been consistently recognized by environmental groups as one of the worst weeds of natural areas (CalEPPC, 1994; 1996; 1999) and has been added to that state's Noxious Weed List (CDFA, 2003). It frequently forms a thick blanket that smothers underlying vegetation, reduces biodiversity, transforms ecosystems and degrades the utility of infested areas. It is also suspected of being toxic to mammals that ingest it and to poison aquatic organisms, but evidence for such poisonings is not yet conclusive. It is still readily available as an ornamental, and this is likely to contribute to its further spread.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Asterales
- Family: Asteraceae
- Genus: Delairea
- Species: Delairea odorata
Notes on Taxonomy and NomenclatureTop of page This vine was first described by Lemaire (1844) as Delairea odorata, but transferred to Senecio (as S. mikanioides) by Harvey (1865) and returned to the original D. odorata by Jeffrey (1986). Several plants in other genera are now considered to be more closely related to D. odorata than is any species in the very large Senecio genus (Jeffrey, 1992; Vincent and Getliffe, 1992).
Two common names are frequently used. In North America and Hawaii, it is commercially available as 'German ivy', and this is the name used in much older literature in the USA. It is called 'Cape ivy' in Australia, and this has now become the preferred common name in North America. It is still called 'German ivy' in New Zealand, where the name 'Cape ivy' is applied to Senecio angulatus (Webb et al., 1988).
DescriptionTop of page D. odorata is a perennial, herbaceous vine with a woody rootstock. At unfavourable sites, it can probably persist as an annual. It is deciduous, but can be evergreen at favourable locations in mild climates. Roots arise from the nodes of stolons and rhizomes, and are simple and shallow, frequently scarcely penetrating the loose surface layer of organic material. Stolons and rhizomes are shiny, with thick cuticles, and the latter frequently have dark purple blotches, or are entirely purple. Frequently large mats are formed up to 30 cm thick on the ground. Stems are twining and can ascend to 8 m. Leaves alternate, more or less succulent, ivy-shaped with 3-5 sharp angles, blades 3-8 cm wide by 3-8 cm long. Leaves produce a distinctive medicinal smell when crushed. Petioles are as long or longer than the leaf, and usually have a pair of flattened, kidney-shaped stipules at the base. Populations without stipules are common in California, but not elsewhere. Inflorescences are in crowded clusters arranged in corymbs, with 10-12 yellow disk flowers. Ray flowers absent. Fruit is a ribbed, reddish-brown, cylindrical achene, about 2 mm long, with a circle of white pappus, 5-6 mm long, at the distal end. Pappus is easily broken, and soon lost.
DistributionTop of page Interestingly, in its native home of South Africa, D. odorata is uncommon, and lacks a common name. It is now widespread in Australia, being found in all states and territories and is probably most invasive in Victoria (Blood 2001). It is widespread on both the North and South islands of New Zealand (Webb et al., 1988). In North America, it is found along 2000 km of coast of California and southern Oregon (Robison et al., 2000; Balciunas et al., 2004). In Hawaii, the largest and most significant problem is on the large island of Hawaii (Jacobi and Warschauer, 1992). Hilliard (1977) notes its presence in Saint Helena, and around Buenos Aires, Argentina, though no herbarium records have been found to confirm these.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Lesotho||Present||Native||Not invasive||Hilliard, 1977|
|Saint Helena||Present||Introduced||Hilliard, 1977|
|South Africa||Restricted distribution||Native||Not invasive||Arnold & de Wet, 1993; Hilliard, 1977|
|-Canary Islands||Present||EPPO, 2014|
|USA||Present||Present based on regional distribution.|
|-California||Widespread||Introduced||1892||Invasive||Munz, 1959; Barkley, 1993; UCJeps, 2003|
|-Hawaii||Restricted distribution||Introduced||1909||Invasive||Haselwood & Motter, 1983; Jacobi & Warshauer, 1992; Wagner et al., 1990|
|-Oregon||Restricted distribution||Introduced||Invasive||Balciunas et al., 2004|
|Argentina||Restricted distribution||Introduced||Hilliard, 1977|
|France||Restricted distribution||Introduced||Royal Botanic Garden Edinburgh, 2003; EPPO, 2014|
|-Corsica||Restricted distribution||Introduced||Royal Botanic Garden Edinburgh, 2003|
|Italy||Restricted distribution||Introduced||Invasive||Catalano et al., 1996; Royal Botanic Garden Edinburgh, 2003; EPPO, 2014|
|Portugal||Restricted distribution||Introduced||Invasive||Royal Botanic Garden Edinburgh, 2003; EPPO, 2014|
|-Azores||Restricted distribution||Introduced||Royal Botanic Garden Edinburgh, 2003; EPPO, 2014|
|Spain||Restricted distribution||Introduced||Torre-Fernandez and Alvarez-Arbesu, 1999; Royal Botanic Garden Edinburgh, 2003; EPPO, 2014|
|UK||Restricted distribution||Introduced||Invasive||Hilliard, 1977; Royal Botanic Garden Edinburgh, 2003|
|-Australian Northern Territory||Restricted distribution||Introduced||Invasive||Blood, 2001; Fagg, 1989|
|-New South Wales||Restricted distribution||Introduced||Invasive||Blood, 2001; Fagg, 1989; Hnatiuk, 1990|
|-Queensland||Restricted distribution||Introduced||Invasive||Blood, 2001; Fagg, 1989|
|-South Australia||Restricted distribution||Introduced||Invasive||Blood, 2001; Fagg, 1989; Hnatiuk, 1990|
|-Tasmania||Restricted distribution||Introduced||Invasive||Blood, 2001; Fagg, 1989; Hnatiuk, 1990|
|-Victoria||Restricted distribution||Introduced||Invasive||Blood, 2001; Fagg, 1990; Fagg, 1989|
|-Western Australia||Restricted distribution||Introduced||Hnatiuk, 1990|
|New Zealand||Widespread||Introduced||1870||Invasive||Webb et al., 1988; Owen, 1996|
History of Introduction and SpreadTop of page D. odorata has been widely used as an ornamental for well over a century, and continues to be widely available. Webb et al. (1988) state the first record of establishment for New Zealand was in 1870. The earliest herbarium record of a naturalized specimen from USA was collected near San Francisco, California in 1892 (UCJeps, 2003; Balciunas et al., 2004). In Hawaii, it was first collected in 1909 (Jacobi and Warshauer, 1992). Dates of introduction to other countries are unknown, but introductions into Europe are probably more recent.
Risk of IntroductionTop of page Further spread is likely, since D. odorata is still readily available for purchase, produced by nurseries and sold via large chain supermarkets and superstores, mail order firms and through websites. However, it is often too common to be profitable for traditional nurseries.
HabitatTop of page In South Africa, its native region, D. odorata appears to have originally been confined to 'mist-veldt' regions, such as those in the Drakensberg Mountains, where it is found along forest edges and as an opportunistic vine exploiting openings in the native forest. Its occurrence at more coastal sites in South Africa may be more recent (Balciunas et al., 2004). Some of the coastal sites are quite arid, to less than 100mm/yr. In California, it occurs mostly in the fog belt along the coast, though a few more inland sites are also known. In California, this popular ornamental most easily establishes in riparian sites with permanent moisture, but then invades from there into drier, more upland sites.
Habitat ListTop of page
|Terrestrial – Managed||Managed forests, plantations and orchards||Present, no further details|
|Managed forests, plantations and orchards||Present, no further details||Harmful (pest or invasive)|
|Managed grasslands (grazing systems)||Present, no further details||Harmful (pest or invasive)|
|Disturbed areas||Present, no further details||Harmful (pest or invasive)|
|Rail / roadsides||Present, no further details||Harmful (pest or invasive)|
|Urban / peri-urban areas||Present, no further details||Harmful (pest or invasive)|
|Terrestrial ‑ Natural / Semi-natural||Natural forests||Present, no further details||Harmful (pest or invasive)|
|Natural grasslands||Present, no further details||Harmful (pest or invasive)|
|Riverbanks||Present, no further details||Harmful (pest or invasive)|
|Wetlands||Present, no further details||Harmful (pest or invasive)|
|Coastal areas||Present, no further details||Harmful (pest or invasive)|
Hosts/Species AffectedTop of page D. odorata is not frequently a weed in crops and pastures, although it may be present on field margins, as well as in irrigation canals and drains surrounding these fields.
Biology and EcologyTop of page Physiology and Phenology
D. odorata is unusual in that it flowers in mid-winter. In the Southern hemisphere, D. odorata flowers between May and August. In California, USA, flowering usually begins in October, peaks in December or January, and is finished by the end of March. In late summer and early autumn, most stems, but not necessarily all, senesce and die back. At about the same time, new shoots begin growing from the persistent rootstock, and these new shoots frequently use the old, dried vines as a trellis to allow them to quickly ascend into and over shrubs and trees.
D. odorata is presumed to be insect pollinated, and this winter-flowering vine is visited by an large array of insects although the principal pollinators have not been documented. The vast majority of seeds produced by D. odorata in North America and perhaps elsewhere are not viable, possibly indicating the lack of effective pollinators. In California, it was previously thought that no viable seeds were produced, but viable seeds have now been discovered (Balciunas, 2001b; Robison, 2001). Hilliard (1977) considers that the cold temperatures present in southern England prevent it from flowering in the open there, noting that it does flower in the warmer Isles of Scilly. D. odorata, however, reproduces very readily from fragments of stem, stolons, or rhizomes as small as 2.5 cm, as long as it includes a node (DiTomaso and Healy, 2004).
Germination requirements of D. odorata seeds are not fully known, but optimal temperatures appear to be 21-26°C (DiTomaso and Healy, 2004). Likewise, other environmental requirements have not been fully investigated, but it demonstrates considerable ecological amplitude. It prefers partial shade, but can tolerate deep shade, and in more moist areas, will thrive in full sun. It is found at elevations above 1500 m in South Africa and Hawaii (Balciunas et al., 2004), but is frost tender. It is occasionally found in arid areas with less than 100 mm annual rainfall, but supplemental moisture is suspected to be present.
In its native range, D. odorata is usually found at edges of native hardwood forests but not in plantations of introduced Eucalyptus or Pinus spp. In its introduced range, D. odorata exploits a wide variety of habitats and occurs in association with hundreds of different plants.
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page Grobbelaar et al. (2003) conducted extensive surveys of the insects associated with D. odorata throughout its native range in South Africa. They found over 400 species of insects associated with this vine, half of which were herbivores, and seven of these merited investigation as potential biological control agents. One pathogen, a still unidentified species of Cercospora, is frequently observed infecting the leaves of D. odorata in South Africa. It causes brown necrotic lesions on the leaves that enlarge and ultimately kill the leaves. More recently, the rust Coleosporium tussilaginis has been found on the leaves of D. odorata growing in California and Oregon, USA and Victoria, Australia and which also occurs on several native Californian species of Senecio.
Means of Movement and DispersalTop of page Natural Dispersal (Non-Biotic)
New infestations of D. odorata are probably primarily the result of dispersal of plant fragments being moved by wind and rain, or floating down streams. Although viable seeds are not common, they are light and attached to silken pappus hairs, making it likely that they are responsible for longer distance dispersion by wind to new sites.
Vector Transmission (Biotic)
Careless disposal of garden waste has led to many waste sites and dumping grounds, both legal and illegal, becoming heavily infested with D. odorata.
Because of its similar appearance to 'true' ivy's, this vine may sometimes be planted unintentionally.
Since D. odorata is not a declared noxious weed in most countries (including USA and Canada) there is little legal restraint to prevent it being carried or shipped across most international borders. It has been and is still widely available from seed mail order companies and via commercial websites as an ornamental species, and most if not all introductions to date have been intentionally as an ornamental species.
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Fruits (inc. pods)||seeds|
|Growing medium accompanying plants||seeds|
|Stems (above ground)/Shoots/Trunks/Branches||stems|
|True seeds (inc. grain)||seeds|
|Plant parts not known to carry the pest in trade/transport|
Impact SummaryTop of page
|Fisheries / aquaculture||Negative|
ImpactTop of page Probably the greatest costs are borne by agencies and individuals trying to get rid of this invasive alien species. For example, Golden Gate National Recreation Area near San Francisco, California, USA has spent over US$600,000 over three years trying to eradicate this vine. Keeping culverts, drains, and roadsides clear of this pest also is problematical since use of herbicides might be highly restricted or even prohibited, and manual removal by hand exorbitantly expensive. It has also been implicated in having caused cattle poisoning in New Zealand (Verdcourt and Trump, 1969).
Environmental ImpactTop of page Although hard to quantify, the environmental impacts of D. odorata are frequently dramatic and devastating. Alvarez (1998) reported that a 3.6 ha infestation of D. odorata near San Francisco increased nearly eight-fold, to 27.2 ha, in nine years. It can quickly form a thick carpet that completely covers the original vegetation on stream banks, forest understories and herbaceous coastal vegetation. After a few years, a thick thatch of dried stems shades out any competing species and the ability to completely cover shrubs and climb high into trees frequently causes their death. Then the fauna that depended on the native vegetation for food and cover is also displaced. A preliminary study found that D. odorata is toxic to fish in an aquarium (Bossard, 2000) and, if this finding is verified, aquatic fauna in adjacent rivers and streams is also threatened.
Impact: BiodiversityTop of page In more severely infested areas, nearly all vegetation except the tallest trees are completely smothered by a thick blanket of D. odorata, thereby greatly reducing the sites' biodiversity, and placing additional stress on endangered species that previously utilized those areas. In a two-year study of the impact of D. odorata on vegetation in three different habitats, Alvarez (1999) found significant negative impacts on species richness, species diversity, seedling abundance, and understorey composition in all three habitats if D. odorata was present.
Threatened SpeciesTop of page
|Threatened Species||Conservation Status||Where Threatened||Mechanism||References||Notes|
|Thysanocarpus conchuliferus (Santa Cruz Island fringepod)||USA ESA listing as endangered species USA ESA listing as endangered species||California||Competition - monopolizing resources||US Fish and Wildlife Service, 2009b|
|Zanthoxylum dipetalum var. tomentosum||CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered species||Hawaii||Competition - monopolizing resources; Competition - smothering; Ecosystem change / habitat alteration||US Fish and Wildlife Service, 2009a|
Social ImpactTop of page D. odorata contains many chemical compounds including xanthones (Catalano et al., 1996) and pyrrolizidine alkaloids (Stelljes et al., 1991). The latter, if ingested in sufficient quantity are toxic to the liver and can lead to renal malfunction. Although mammalian poisoning does not appear to be well documented, there are a large number of unsubstantiated reports concerning poisoning by D. odorata. A variety of web sites warn of the possible toxic impacts of this plant to infants (e.g. CCCF, 2003) and pets (e.g., ASPCA, 2003). Most of the many parks along the coast of California, USA are impacted to a lesser or greater extent by presence of D. odorata. Park managers who seek to prevent further erosion of their park's biodiversity and ecological values are forced to divert their limited resources from other critical needs. This may make the parks less attractive to visitors.
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly adaptable to different environments
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Highly mobile locally
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Negatively impacts animal health
- Negatively impacts tourism
- Reduced amenity values
- Reduced native biodiversity
- Competition - monopolizing resources
- Competition - smothering
- Highly likely to be transported internationally deliberately
- Difficult/costly to control
UsesTop of page Since it flowers in mid-winter, it is frequently the most readily available nectar source at that time, especially in heavily infested areas. Numerous insects are attracted to its flowers, including migrating monarch butterflies (Stelljes and Seiber, 1990). Its ability to survive neglect contributes to its lasting popularity as a houseplant and garden ornamental.
Similarities to Other Species/ConditionsTop of page In South Africa, there are about six similar vines in the closely related genus Senecio, but which lack the flattened stipules that are almost always present in South African populations of D. odorata. In other countries, it is most frequently mistaken for a 'true' ivy such as Hedera helix (English ivy) or H. canariensis (Algerian ivy). Both of these have darker, more leathery leaves, lack D. odorata's medicinal odour, and since they are in the family Araliaceae, have vastly different flowers.
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.Cultural Control
Control of D. odorata with fire or grazing animals has not been reported, although using goats might be feasible. However, D. odorata contains pyrrolizidine alkaloids, which are known to be potent mammalian hepato-toxins.
Although very labour intensive, hand-pulling of D. odorata is usually the preferred control method. To prevent new infestations in other areas, the plant material that has been removed must be disposed of carefully.
Clopyralid has been used successfully in Australia (Fagg, 1989). In California, glyphosate alone provided only very temporary control (Bossard and Benefield, 1995), but when a mixture of glyphosate + triclopyr + silicone surfactant in water was used, it provided successful control after two applications (Bossard, 2000). Damage to non-target vegetation is likely, and care should be taken to minimize this.
There are no approved biological control agents available to manage D. odorata. However, in the United States, a project to develop such agents was launched by USDA-ARS in 1998 (Balciunas and Archbald, 1999). Surveys were conducted in South Africa for natural enemies of this vine and during two years research, several hundred insects attacking D. odorata were identified (Grobbelaar et al., 2003). Two of these insect species, the Cape ivy gall fly (Parafreutreta regalis Munro) and the Cape ivy stem moth (Digitivalva delaireae Gaedike & Kruger) are currently being evaluated at the USDA-ARS quarantine facility in Albany, California and at a facility in Pretoria, South Africa to determine if they are safe enough to release in North America (Balciunas, 2001a).
Whatever control method is used, careful monitoring and removal of any resprouts and seedlings is essential, or within a matter of months the treated area will become indistinguishable from adjacent untreated areas.
ReferencesTop of page
Alvarez ME, 1998. Management of Cape-ivy (Delairea odorata) in the Golden Gate National Recreation Area. In: Kelly M, Wagner E, Warner P, eds. Proceedings of the California Exotic Pest Plant Council Symposium Vol. 3, Concord, California, 91-95.
Alvarez ME, 1999. Community level consequences of a biological invasion: effects of a non-native vine on three plant communities. MA Thesis. Sonoma State University, California, USA.
Arnold TH, de Wet BC, 1993. Plants of southern Africa: names and distribution. Memoirs of the Botanical Survey of South Africa, No. 62. Pretoria, Republic of South Africa: Botanical Research Institute.
ASPCA, 2003. Poisonous Plants. American Society for the Prevention of Cruelty to Animals, USA. http://www.aspca.org.
Balciunas J, 2001. Biological control of Cape ivy project reaches milestone. CalEPPC News, 9:3-4.
Balciunas J, 2001. Viable seed production by Cape ivy in California finally confirmed. CalEPPC News, 9:13.
Balciunas J, Archbald G, 1999. Cape ivy biological control. Noxious Times, 2:8-9.
Balciunas J, Grobbelaar E, Robison R, Neser S, 2004. Distribution of Cape ivy (Delairea odorata Lem.), a growing threat to western riparian ecosystems. Weed Technology (in press).
Barkley TM, 1993. Senecio: groundsel, ragwort, butterweed. In: Hickman JC, ed. The Jepson Manual: Higher Plants of California. Berkeley, USA: University of California Press, 336-342.
Blood, K, 2001. Delairea odorata. In: Glen Osmond. Environmental Weeds: a field guide for SE Australia. South Africa: Cooperative Research Centre for Weed Management Systems, 104-105.
Bossard C, Benefield C, 1995. The war on German ivy: good news from the front. In: Proceedings of the Symposium. Sacramento: California Exotic Pest Plant Council, 1-2.
Bossard CC, 2000. Delairea odorata. In: Bossard C, Randall J, Hoshovsky M, eds. Invasive plants of California's wildlands. Berkeley, USA: University of California Press, 154-158.
CalEPPC, 1994. Exotic Pest Plants of Greatest Ecological Concern in California. California Exotic Plant Pest Council, USA.
CalEPPC, 1996. The CalEPPC List: Exotic Pest Plants of Greatest Ecological Concern in California as of August 1996. California Exotic Plant Pest Council, USA.
CalEPPC, 1999. The CalEPPC List: Exotic Pest Plants of Greatest Ecological Concern in California. California Exotic Plant Pest Council, USA.
CCCF, 2003. Toxic Plant List. Canadian Child Care Federation, Canada. http://www.cfc-efc.ca/docs/cccf/rs029_en.htm.
CDFA, 2003. The List of California's Noxious Weeds. California Department of Food and Agriculture, USA. http://pi.cdfa.ca.gov/weedinfo/Index.html.
DiTomaso JM, Healy EA, 2004. Weeds of California and other Western States. Division of Natural Resources, University of California (in press).
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Fagg PC, 1989. Control of Delairea odorata (Cape ivy) in native forest with the herbicide clopyralid. Plant Protection Quarterly, 4:107-110.
Grobbelaar E, Balciunas JK, Neser O, Neser S, 2003. South African insects for biological control of Delairea odorata. In Kelly M, ed. Proceedings of the California Exotic Pest Council Symposiums, Volume 6,: 2000, 2001, 2002, 16-28. Concord, California, USA.
Harvey WH, 1865. Compositae Juss. In: Harvey WH, Sonder OW, eds. Flora Capensis: being a systematic description of the plants of the Cape Colony, Caffraria, & Port Natal. Vol. III. Rubiaceae to Campanulaceae. London, UK: Lovell Reeve & Co. Ltd, 44-530.
Haselwood EL, Motter GG, eds, 1983. Handbook of Hawaiian weeds, edition 2. Honolulu, Hawaii, USA: University of Hawaii Press.
Hilliard OM, 1977. Compositae in Natal. Pietermaritzburg, South Africa: University of Natal Press.
Hnatiuk RJ, 1990. Census of Australian Vascular Plants. Australian Flora and Fauna Series Number 11. Canberra, Australia: Australian Government Publishing Service.
Jacobi JD, Warschauer FR, 1992. Distribution of six alien plant species in upland habitats on the island of Hawaii. In: Stone CP, Smith CW, Tunison JT, eds. Alien Plant Invasions in Native Ecosystems of Hawai'i: Management and Research. Honolulu, Hawaii, USA: University of Hawaii Cooperative National Park Resources Studies Unit, 155-188.
Jeffrey C, 1986. Notes on Compositae IV: The Senecioneae in East Tropical Africa. Kew Bulletin, 41:873-943.
Jeffrey C, 1992. Notes on Compositae, VI: The tribe Senecioneae (Compositae) in the Mascarene Islands with an annotated world check-list of the genera of the tribe. Kew Bulletin, 47:49-109.
Lemaire C, 1844. Delairea, ad synantheras genus novum spectans. In: Milne-Edwards M, Brongniart MMAD, Decaisne J. Annales des Sciences Naturelles. Paris, France: Fortin, Masson et Cie), Libraires-Éditeurs, 379-381.
Munz PA, 1959. A California flora. Berkeley, USA: University of California Press.
Owen SJ, 1996. Ecological weeds on conservation land in New Zealand: A database. Department of Conservation, Wellington, New Zealand: DOC Science Publications. http://www.hear.org/weedlists/other_areas/nz/nzecoweeds.htm.
Robison R, Grotkopp E, Yacoub R, 2000. Cape ivy (Delairea odorata) distribution in California and Oregon. In: Kelly M, Howe M, Niell B, eds. Proceedings of the California Exotic Pest Plant Council Symposium, Vol. 5, Sacramento, California, 82-84.
Robison, R, 2001. Cape ivy germinating in California and Oregon. CalEPPC News, 9:8-9.
Royal Botanic Garden Edinburgh, 2003. Flora Europaea, Database of European Plants (ESFEDS). Edinburgh, UK: Royal Botanic Garden. http://rbg-web2.rbge.org.uk/FE/fe.html.
Stelljes ME, Kelley RB, Molyneux RJ, Seiber JN, 1991. GC-MS determination of pyrrolizidine alkaloids in four Senecio species. Journal of Natural Products, 54(3):759-773
Torre-Fernández F de la, ¦lvarez-Arbesú R, 1999. Control of noxious weeds in sensitive areas. In: Proceedings, Invasoras Lenhosas. Geres, Spain: Sociedade Portuguesa Ciencias Florestais, 203-208.
UCJeps, 2003. SMASCH Project: Specimen Management System for California Herbaria. University and Jepson Herbaria, California, USA. http://www.mip.berkeley.edu/www_apps/smasch/.
US Fish and Wildlife Service, 2013. In: Endangered and Threatened Wildlife and Plants; Review of Native Species That are Candidates for Listing as Endangered or Threatened; Annual Notice of Findings on Resubmitted Petitions; Annual Description of Progress on Listing Actions. 78(226) US Fish and Wildlife Service, 70104-70162. https://www.gpo.gov/fdsys/pkg/FR-2013-11-22/pdf/2013-27391.pdf
Verdcourt B, Trump EC, 1969. Common Poisonous Plants of East Africa. London, UK: Collins, 158-161.
Vincent PLD, Getliffe FM, 1992. Elucidative studies on the generic concept of Senecio. Botanical Journal of the Linnaean Society, 108:55-81.
Wagner WL, Herbst DR, Sohmer SH, 1990. Manual of Flowering Plants of Hawaii. Bernice Pauahi Bishop Museum Special Publication 83. Honolulu, Hawaii, USA: University of Hawaii.
Webb CJ, Sykes WR, Garnock-Jones PJ, 1988. Flora of New Zealand Volume IV. Naturalised Pteridophytes, Gymnosperms and Dicotyledons. Christchurch, New Zealand: DSIR Botany Division, 1365 pp. http://floraseries.landcareresearch.co.nz/pages/Book.aspx?fileName=Flora%204.xml
Distribution MapsTop of page
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