Dew-flower (Drosanthemum floribundum (Haw.) Schwantes) is a perennial succulent plant native to coastal environments in South Africa. It is characterised by short, cylindrical leaves with a generally rounded apex and densely covered with hyaline papillae that give it a glossy appearance, as if covered with morning dew. It belongs to the Aizoaceae family, the same as the cat’s claw or sea-fig (Carpobrotus spp.), with flowers of similar structure but in the case of the dew-flower much smaller, maximum 2.5 cm, of variable pink colour, often pale and sometimes of a more intense hue. The fruits are pentalobulated. You can find more details in the Flora Catalana data sheet.
Flowering plants in Cadaquès and L’Escala, the latter also bearing fruit (Photos: J. López-Pujol and C. Gómez-Bellver, respectively).
In its native area it generally grows in coastal habitats, occupying rocky, sandy or clayey soils. In these regions the climate is relatively warm and the rainfall is low, although some of the water may also come from sea breezes or fog. Overall, we are talking about a Mediterranean-type ecosystem similar to our own, with plant communities similar to those found, for example, on the Costa Brava. For this reason, and as with other non-native plants, this species adapts very well to the natural environment of our coastline.
Plants in their littoral habitat in South Africa, showing the variability of the pink tones of the flowers (iNaturalist photos by marinavw and dinevanzyl, respectively).
Drosanthemum is widely used in gardening, especially for making live carpet coverings. Its rapid growth and high density of flowers make it very attractive. In several gardens or houses it is used to cover walls or slopes forming a kind of hanging cascade, as it is not a climbing plant. It requires drained soil and reproduces easily vegetatively by means of fragments, being a plant that withstands sunlight well and can live with little water, with practically no maintenance. It flowers from spring until the middle or end of summer.
It is found sub-spontaneously in the Mediterranean area, especially in the north-western part (GBIF, iNaturalist). It occurs in many parts of the Catalan coast, including a large part of the Costa Brava, especially where there are gardens and houses nearby. Pruning debris, or the fragmentation of the stems as they fall down the slope, are the main source of the species’ first colonization or spread. This is particularly worrying as it affects the habitat of coastal cliffs with endemic Limonium spp.
L’Escala, plants escaped from a nearby garden, very close to the HCI 1240 habitat, the one being monitored for invasive plants affecting endemics (Photo: C. Gómez-Bellver).
It seems that this plant is expanding in our coastal area. In order to find out objectively whether this is true, within the LIFE medCLIFFS project, a group of volunteers is monitoring its populations in several stretches (especially along the Camí de Ronda), as well as those of another thirty or so invasive or potentially invasive species. At the end of the project we will be able to draw reliable conclusions in this regard. What we have already verified is that in some parts of the Cap de Creus Natural Park there are some groups of subspontaneous plants, an area where their presence may be of greater concern.
In short, we do not consider Drosanthemum floribundum to be as worrying as Carpobrotus spp. for example, but it does show a clear adaptation to our territory and an evident degree of competition for space and light. It can form such a dense ground cover that it prevents seedlings of endemic species from germinating or growing, while also affecting the development of other organisms such as lichens and mosses.
Begur, displacing other plants and organisms; on the right, in the central part, a group of plants in Paraje de Tudela in the Cap de Creus Natural Park, occupying the space of some endemic plants and species characteristic of the habitat (Photos: C. Gómez-Bellver).
Text: Carlos Gómez Bellver.
