Invasive species: Hottentot fig (Carpobrotus edulis)

Part of a series showing invasive alien or exotic species (non-native and spreading) in Europe. 𝘊𝘢𝘳𝘱𝘰𝘣𝘳𝘰𝘵𝘶𝘴 𝘦𝘥𝘶𝘭𝘪𝘴 (Aizoaceae), originally from coastal regions of South Africa but introduced outside its native range either as an ornamental plant or for soil stabilization, is one of the most widespread invasive species worldwide. The plants shown here were observed on the northern coast of Corsica, near Ersa. The species is easily confused for the related 𝘊. 𝘢𝘤𝘪𝘯𝘢𝘤𝘪𝘧𝘰𝘳𝘮𝘪𝘴, and hybridization between these species has resulted in a range of ill-defined, vigorous hybrid taxa that are often simply referred to as 𝘊𝘢𝘳𝘱𝘰𝘣𝘳𝘰𝘵𝘶𝘴 𝘦𝘥𝘶𝘭𝘪𝘴 for convenience. Technically, 𝘊. 𝘦𝘥𝘶𝘭𝘪𝘴 (𝘴𝘵𝘳𝘪𝘤𝘵𝘰 𝘴𝘦𝘯𝘴𝘶) has yellow flowers, fading to light pink with age, and the cut leaves have an equilateral triangular section. In contrast, 𝘊. 𝘢𝘤𝘪𝘯𝘢𝘤𝘪𝘧𝘰𝘳𝘮𝘪𝘴 has vibrant magenta petals and leaves with an isosceles triangular section (i.e. having two sides of equal length).

A stress-tolerator with succulent leaves, salt tolerance, an extremely adaptable form of photosynthesis (crassulacean acid metabolism; CAM), capacity to survive excessively high light intensities, effective fruit and seed production, and clonal reproduction from fragments and lateral stems, it spreads over dunes and through costal vegetation. It reduces local biodiversity, alters plant-pollinator networks and plant-herbivore relationships, and acidfies the soil. Control methods may include herbicide use, but the most effective action is pulling up the plants mechanically, often by hand, leaving the remains to dry out on rocks or other inert surfaces. Biological control methods are being developed using the host-specific scale-insect 𝘗𝘶𝘭𝘷𝘪𝘯𝘢𝘳𝘪𝘦𝘭𝘭𝘢 𝘮𝘦𝘴𝘦𝘮𝘣𝘳𝘺𝘢𝘯𝘵𝘩𝘦𝘮𝘪, and a combined use of mechanical and biological control is being investigated.

Photograph of the flowers by Francesco Raineri, published under a CC BY 4.0 deed (creativecommons.org/licenses/by/4.0/deed.en )

𝗧𝗵𝗶𝘀 𝗰𝗵𝗮𝗻𝗻𝗲𝗹 𝗶𝘀 𝗻𝗼𝘁 𝗺𝗼𝗻𝗲𝘁𝗶𝘇𝗲𝗱.

𝗥𝗲𝗹𝗮𝘁𝗲𝗱 𝗽𝗲𝗲𝗿-𝗿𝗲𝘃𝗶𝗲𝘄𝗲𝗱 𝗹𝗶𝘁𝗲𝗿𝗮𝘁𝘂𝗿𝗲:

Campoy, J. G., Acosta, A. T. R., Affre, L., Barreiro, R., Brundu, G., Buisson, E., … Fagúndez, J. (2018) Monographs of invasive plants in Europe: 𝘊𝘢𝘳𝘱𝘰𝘣𝘳𝘰𝘵𝘶𝘴. Botany Letters, 165(3–4), 440–475. doi.org/10.1080/23818107.2018.1487884

Dalle Fratte, M., Bolpagni, R., Brusa, G., Caccianiga, M., Pierce, S., Zanzottera, M., Cerabolini, B.E.L. (2019) Alien plant species invade by occupying similar functional spaces to native species. Flora,
257: 151419. doi.org/10.1016/j.flora.2019.151419.

Guo W.-Y., van Kleunen, M., Winter, M., Weigelt, P., Stein, A., Pierce, S., Pergl, J., Moser, D., Maurel, N., Lenzner, B., Kreft, H., Essl, F., Dawson, W. & Pysek, P. (2018) The role of adaptive strategies in plant naturalization. Ecology Letters, 21(9): 1380–1389. onlinelibrary.wiley.com/doi/10.1111/ele.13104

Guo, W.-Y., van Kleunen, M., Pierce, S., et al. (2019) Domestic gardens play a dominant role in selecting alien species with adaptive strategies that facilitate naturalization. Global Ecology & Biogeography, 28: 628–639. doi.org/10.1111/geb.12882

Guo, K., Pyšek, P., Chytrý, M., Divíšek, J., Lososová, Z., van Kleunen, M., Pierce, S., & Guo, W-Y (2022) Ruderals naturalize, competitors invade: Varying roles of plant adaptive strategies along the invasion continuum. Functional Ecology, 36: 2469–2479. doi.org/10.1111/1365-2435.14145

Guo, K., Pyšek, P., van Kleunen, Kinlock, M., N.L., Lučanová, M., Leitch, I.J., Pierce, S., et al. (2024) Plant invasion and naturalization are influenced by genome size, ecology and economic use globally. Nature Communications, 15: 1330. doi.org/10.1038/s41467-024-45667-4

Guo, K., Pyšek, P., Chytrý, M., Divíšek, J., Sychrová, M., Lososová, Z., van Kleunen, M., Pierce, S. & Guo W.-Y. (2024) Stage dependence of Elton’s biotic resistance hypothesis of biological invasions. Nature Plants. doi.org/10.1038/s41477-024-01790-0

Núñez-González, N., Rodríguez, J., González, L. (2021) Managing the invasive plant 𝘊𝘢𝘳𝘱𝘰𝘣𝘳𝘰𝘵𝘶𝘴 𝘦𝘥𝘶𝘭𝘪𝘴: is mechanical control or specialized natural enemy more effective? Journal of Environmental Management, 298: 113554. doi.org/10.1016/j.jenvman.2021.113554