Holly leaved senecio is native to the Cape region of South Africa. It is uncertain when the plant was introduced into Australia, but it was first recognised as naturalised in 1986 in the Albany district of Western Australia. The plant is particularly invasive in open damp areas, and has the ability to dominate understorey vegetation in these conditions.
In South Africa the natural range of holly leaved senecio is restricted to a narrow coastal strip of the eastern Cape. However, even in this area it has become a weed in disturbed sites and agricultural land. Holly leaved senecio has spread widely throughout New Zealand in the last 20 years, and shows continuing evidence of rapid spread. In Australia, holly leaved senecio now occurs throughout woodlands near Albany, Western Australia, and on the central coast of NSW, at Bundeena.
The flowers of holly leaved senecio are pollinated by bees. It reproduces from cuttings, fallen branches and wind-dispersed seed. While the primary mechanism of spread is seed dispersal, it is able to take root from fallen branches. Wind dispersal of the seed allows it to spread some distance from the original infestation, and seeds may remain viable in the soil for extended periods of time.
Germination of holly leaved senecio seed is encouraged by fire. The occurrence of fire followed by good rains has proved to substantially promote its spread throughout its current range in Western Australia. It is believed that slashing fire breaks or disturbing the soil in the vicinity of the plant or its seedbank also assists the spread of seeds.
Holly leaved senecio is a member of the daisy family. It is a stout medium-lived perennial (sometimes annual) with stems 1.0–1.5 m, occasionally to 2 m, tall.
The stems, which may branch in older plants, can be 80 mm in diameter at the base of large plants. All stems produce flowers on widely spaced branches.
The leaf’s length is approximately 1.5 times its width and it is widest just above the leaf centre. Leaves are serrated and often coarsely toothed near the leaf stalk, which can make them rather prickly to touch. The leaves are 100–150 mm long at the base of the plants, decreasing to 30–50 mm near the top of the stems, where they are less serrate. The leaves are a distinctive feature of the holly leaved senecio and make it relatively easy to identify, even when young.
The flowers of holly leaved senecio can range from two to three per plant to several hundred. They are actually combined inflorescences, which are many tiny flowers situated in the central part of the composite flower. The inflorescences have supplementary bracts (a modified tiny leaf around the flower like a bud) 3.0–5.5 mm long, are yellow in the centre, and are surrounded by mauve petals, making the holly leaved senecio an eye-catching plant.
The developing seed heads (derived from the inflorescences) turn into white fluffy balls by the time the seed has formed and ripened. In warm and wet conditions holly leaved senecio will germinate within two weeks.
Holly leaved senecio can be confused with wild cineraria (Senecio elegans) at a distance, but up close the two plants are quite different. Wild cineraria is a much softer looking plant, with more succulent and hairy leaves and stems than holly leaved senecio. Wild cineraria is also an annual plant.
It occurs naturally in shrubland and near waterways and more often in open, wet areas in its native habitat. It grows frequently on hillsides, coastal dunes and disturbed areas such as roadsides.
CRC for Australian Weed Management: Leisl van der Wall (Kirstenbosch National Botanic Garden, South Africa), Karin Baker (Friends of Mt Adelaide and Mt Clarence Nature Reserve), Sandy Lloyd (WA Agriculture / Weeds CRC), Rod Randall (WA Agriculture / Weeds CRC).
Holly leaved senecio may potentially be eradicated before it becomes a problem in other locations in Western Australia. Any new outbreaks should be reported immediately to your local council weed officer. Do not try to control holly leaved senecio without their expert assistance. Control effort that is poorly performed or not followed up can actually help spread the weed and worsen the problem.
Holly leaved senecio (Senecio glastifolius) is not declared in NSW under the Noxious Weeds Act 1993.