Today in THE FEATURED PLANT section we will talk about the sea fig plants (Carpobrotus spp.), two species native to the Cape Region of South Africa and widely spread along the Mediterranean coasts.
The sea fig plant
The sea fig, also called “cat’s claw” in Spain, “hottentot fig” or “sally-my-handsome”, is a creeping plant with numerous green to reddish fleshy leaves that may resemble the elongated claw of a cat. Its flowers are large and very showy, ranging in colour from white to deep pink. If you want to know how to identify it in more detail, you can consult its data sheet available here (in Catalan).
This species was introduced in the Iberian Peninsula as an ornamental plant and to control erosion in coastal areas. Its ability to grow in poor, coastal soils makes it a highly valued plant for preventing erosion of slopes and dunes. However, these same features, joint to its rapid and competitive growth, have made it an invasive behaviour in various coastal areas in the Mediterranean basin.
Although they are not usually differentiated due to their great similarity and the use of the same name, both Carpobrotus acinaciformis and Carpobrotus edulis can be found abundantly on the Mediterranean coast. The differentiation of these species is a challenge even for botanists, as they are very similar both in appearance and habitat, and both show a strong invasive character and originate from the same region.
The best way to identify them is usually to look at leaf morphology and flower colour: C. acinaciformis has an isosceles triangle-shaped leaf section (2 long sides and a narrow one), more curved leaves and pink or purple flowers; whereas C. edulis has an equilateral triangle-shaped leaf section (3 equal sides), more or less straight leaves and flowers that can range from white to deep pink.
Due to the difficulty to differentiate both species, in LIFE medCLIFFS we consider them as the same plant for data collection by observers and volunteers, for modelling their spread and for eradication work.
Subtropical delicacy and medicine
The name Carpobrotus comes from the Greek “karpos”, meaning fruit, and “brota”, meaning edible thing. Several species of this genus are edible and have historically been used in South African cuisine. Although the leaves are also edible, the fruits are particularly notable and have been used to make preserves, jams and marmalades with a sour taste. Both spices (C. acinaciformis and C. edulis) are considered safe for human consumption whether raw or cooked. In fact, due to their high nutritional value and antioxidant properties, their fruits have been compared to oranges, apples or grapes.
In addition to its culinary uses, C. edulis has a long list of uses in traditional South African medicine. It has been used to treat diabetes, dysentery, diarrhoea, hypertension, some symptoms of tuberculosis and other respiratory infections, toothache and earache, facial eczema and wounds, burns and mosquito and spider bites, among others. Some of these medicinal uses have been validated by the scientific community, especially the antimicrobial, antioxidant, antiproliferative, anti-inflammatory, antidiabetic and neuroprotective properties.
Eradication methods in LIFE medCLIFFS
The method used for the eradication of Carpobrotus is manual or mechanical uprooting, where the root is removed and the remains are piled in close confined piles that degrade over time. In Cap de Creus it has been in practice for years, and its maintenance is still carried out through numerous initiatives and/or volunteer and environmental education organisations (Fundesplai, La Sorellona-Decathlon, Biosfera…) that collaborate directly or indirectly in the tasks of controlling invasive exotic flora in the Natural Park.
Manual or mechanical grubbing is one of the most common methods for controlling the spread of Carpobrotus. However, in LIFE medCLIFFS we want to go further and extend the work to areas that are difficult to access such as slopes and cliffs, where the plant usually forms dense mats, carrying out for the first time removal work on vertical terrain. This measure will be carried out in conjunction with eradication in other areas where the high risk of invasion of the species may affect endemic flora such as the limoniums present in Cap de Creus (Limonium tremolsii and Limonium geronense) and the endangered species Seseli farrenyi.
This work would not make sense if we did not address the sources of plant propagation, such as the coastal gardens with invasive plants present in the area of influence of the Cap de Creus Natural Park. These gardens are often the points of origin of fragments or seeds of invasive plants that take root and end up forming dense plant covers on the adjacent slopes and cliffs. LIFE medCLIFFS is making efforts to contact the owners of such gardens to agree on the removal of invasives within their properties. If no action is taken on coastal gardens, eradication efforts on the cliffs will soon be overtaken by new invasions.
Text: Arnau Bosch Guiu.