Today’s THE FEATURED PLANT section focuses on gazania (Gazania rigens), a beautiful plant with a serious impact on the habitats of Cap de Creus, which is why it is one of the targeted plants in LIFE medCLIFFS.
An alien plant very common to natural coastal areas
Gazania belongs to the same family as daisies, i.e. it belongs to the Asteraceae, and was introduced in Spain in the 1970s from South Africa to be used in gardening.
In our country it is very popular as an ornamental plant, because of its bright yellow and orange flowers that fill any corner with life, and also because of its ease of growth.
However, it is just this ability to grow in almost any environment that makes it so easy to escape from gardens to the natural environment, becoming an invasive plant in a habitat such as the Mediterranean sea cliffs in the Costa Brava.
The observations recorded so far through the LIFE medCLIFFS Observer Network indicate that the gazania invasion is mainly located in the Cap de Creus area. However, the species has also been observed in other areas of the central and southern Costa Brava, albeit more sporadically.
Why is gazania invasive?
Gazania rigens is a species with a good set of biological and ecological adaptations that make it very easy to colonise coastal areas:
- The species grows up to half a metre, not excessively tall and with a slightly creeping habit, which gives it great wind resistance.
- It grows well in all types of soil, also in cracks or rocky surfaces with shallow soil, where its seeds germinate easily.
- It can reproduce by seed or by stem fragments or rhizomes, forming a dense and continuous vegetation cover.
- It produces a large number of fruits (ovoid achenes covered with long pappus hairs) which, although wind can disperse them up to 1 km away, often fall close to the parent plants and fill the soil seed bank, germinating easily when conditions are favourable.
- It is perennial, forming stable green areas that can be maintained for years, either through germination of its seeds or through rooting of lower plant stems, causing the number of gazania seeds in the soil seed bank to increase year after year and preventing other species from germinating.
- The bushes are whitish-green in colour due to the pilosity of the leaves, which are lanceolate and can be simple or lobed. This pilosity provides effective protection against overexposure to the sun and contact with saline environments..
How to identify it?
The easiest way to identify gazania is through a flowering bush.
Although it flowers mainly between May and August, in Cap de Creus and along the coast we can find gazania plants in flower almost all year round.
The flower heads have tubular flowers in the centre and ligulate flowers on the margin, with yellowish to orange colours, and quite diverse: sometimes, the ligule can have a transverse black band near the base or a clear macula in the central part.
You can see some of these differences through the observations of gazania recorded in the LIFE medCLIFFS Observer Network, or check all the morphological details here
How does gazania impact the cliffs?
In the coastal cliffs, gazania competes with native flora for both pollinators and space.
Pollinators are attracted to the large and bright flowers of gazania, rather than the small, inconspicuous flowers of native plants, reducing the chance that the native flora can be pollinated and form seeds.
Furthermore, as mentioned above, gazania covers very densely all the available land and prevent the germination of seeds of native plants. This is particularly problematic for endemic species with small populations, such as Limonium geronense and Limonium tremolsii.
What is LIFE medCLIFFS doing to avoid the impact of gazania?
During 2023, LIFE medCLIFFS will start a series of demonstrative interventions for the eradication and control of gazania. Both manual removal methods and a experimental chemical treatment will be used, and the experience gained will allow us to development of best practices, currently non-existent, for the effective control of this invasive species.
The intervention areas in the cliffs are located mainly in Port de la Selva, specifically in the area of the S’Arenella lighthouse, and in Cadaqués, on the coastal strip between Es Pianc and Calders, and in the area of S’Alqueria Petita.
In addition, the gazania that grows in the private gardens that collaborate with us will also be eliminated, in order to prevent this species from colonising the cliffs again.
We need you!
If you own a garden by the sea in Cadaqués, Port de la Selva or Roses with gazania plants, please contact us and help us to reduce the impact of this species in an area of great ecological, landscape and social value such as Cap de Creus.
To check if the plants you have are gazania, please check the simplified LIFE medCLIFFS factsheet or the complete factsheet in the Flora Catalogue of Flora Catalana, where you can find photographs and descriptions that will help you to identify it (sorry, only in Catalan for the moment!), or you can use the iNaturalist app.