Arctotheca calendula in North Africa
Arctotheca calendula (Asteraceae: EPPO List of Invasive Alien Plants) is a short lived herbaceous plant which was first introduced into Europe as a garden ornamental in the early 18th century. Native to South Africa, A. calendula is recorded in the EPPO region in countries in the Mediterranean basin. In North Africa, A. calendula is present over a wide area in northern Tunisia and a smaller area in north-east Algeria. In these areas it has spread considerably since it was first recorded, with populations ranging from 6 m2 in pasture and crops (in Algeria) to covering 25 ha along roadsides and wet meadows (in Tunisia). The pathway of introduction in Tunisia is thought to be as a contaminant of clover seed imported from Australia, whereas for Algeria, the pathway of introduction is unknown but could be as a contaminant of peanut seed. Spread within each country may be facilitated by migratory birds and dispersal by livestock. Water and wind can also act to spread propagules. Arctotheca calendula is resistant to a number of herbicides which reduces the likelihood of success using this control method. Manual control methods can be applied, including hand pulling though this would be labour intensive where the species covers large areas.
Sources
Sakhraoui N, El Mokni R, Hadef A, Rais H, Verloove F, Essl F (2024) Current distribution and status of Arctotheca calendula (L.) Levyns (Asteraceae) in Algeria and Tunisia (North Africa). BioInvasions Records 13(2), 319-333. https://doi.org/10.3391/bir.2024.13.2.03.