Broad leaved climber, leaves with angular contour, and small yellow flowers.

Scientific name: Delairea odorata Lem.

Common names: Cape ivy, German ivy

Family: Asteraceae (Compositae)

Status in Portugal: invasive species

Risk Assessment score: (in development)

Synonymy: Senecio mikanioides Otto ex Walpers

Last update: 08/07/2014

How to recognise

Climbing herb, woody on the base, up to 5 m.

Leaves: semi-fleshy, from deltoid to orbicular, lustrous, with a cordate blade on the base and with 3-5 acute lobes on each surface, giving them an angular look; petiole with two small auricles on the base.

Flowers: yellow and tubular, arranged in capitula, which in turn are arranged in dense, axillary panicles.

Fruits: cypselas 2-2,5 mm long, that has a pappus with white hairs.

Flowering: December to February.

Delairea odorata (Cape ivy)

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Deltoid and lustrous leaves, with 3-5 lobes on each sur-

face, giving them an angular look

Similar species

It can be grossly mistaken with Bryonia cretica L. when flowers are not visible. However, the indentation of the leaves of Delairea odorata is more acute and regular. When in flowering, it is completely different, once B. cretica has white flowers.

Characteristics that aid invasion

It reproduces by seed, producing a high amount of seeds.

It also propagates vegetatively, by stem fragments that easily detach, root and originate new plants.

ORIGIN AND DISTRIBUTION

Native distribution area

South Africa (Cape region).

Distribution in Portugal

Mainland Portugal (Minho, Douro Litoral, Beira Litoral, Estremadura), Azores archipelago (islands of São Miguel, Santa Maria, Terceira, Graciosa, São Jorge, Pico, Faial), Madeira archipelago (island of Madeira).

Other places where the species is invasive

Australia, New Zealand, west USA (California), Asian Southwest, several countries in western Europe.

Introduction reasons

For ornamental purposes.

Preferential invasion environments

It frequently invades banks of watercourses, hedgerows and slopes, ruderal environments and communities of thorny shrubs.

It also proliferates vigorously in gardened areas where it was initially planted.

IMPACTS

Impacts on ecosystems

It forms impenetrable mats that smother the trees, shrubs and grasses of other species, leading to their death and preventing the development of native vegetation.

It also proliferates vigorously in gardened areas where it was initially planted.

Other impacts

All the parts of the plants are toxic, therefore being noxious for animals.

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Delairea odorata (Cape ivy)

CONTROL

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Delairea odorata include:

Physical control

Hand pulling (preferential methodology). In more compact substrates, hand pulling should be made during the rainy season to facilitate the removal of the root system. It should be guaranteed that there are no large fragments left in the ground, which root easily and originate new invasion foci. All pulled material should be removed from the location for posterior destruction.

Physical + chemical control

Cut stump method. Cut the stems as close to the ground possible and apply herbicide a few seconds afterwards (active substance: glyphosate, triclopyr) to the cut surface. Some authors refer that the sprouts are more sensitive to herbicides, so alternatively, the application of herbicide may be made over the sprouts.

Chemical control

Foliar application of herbicide: applied in extensive areas that are invaded by the species. Spray with herbicide (active substance: glyphosate, triclopyr) limiting its application to the target species.

For additional information, visit the webpage www.invasoras.pt and/or contact us at invader@uc.pt.

REFERENCES

CABI (2012) Delairea odorata. In: Invasive Species Compendium. CAB International, Wallingford, UK. Available: www.cabi.org/isc [Retrieved 12/11/2012].

Jardim R, Silva L, Gallo AG (2008) Delairea odorata Lem. In: Silva L, Land EO, Luengo JLR (eds) Flora e fauna terrestre invasora na Macaronésia. Top 100 nos Açores, Madeira e Canárias. Arena, Ponta Delgada, pp. 248-250.

Marchante E, Freitas H, Marchante H (2008) Guia prático para a identificação de plantas invasoras de Portugal Continental. Imprensa da Universidade de Coimbra, Coimbra, 183pp.

USDA, NRCS. (2012) The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. Available: http://plants.usda.gov [Retrieved 12/11/2012].

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Delairea odorata (Cape ivy)