The residents of the Swiss canton of Valais are used to seeing their mountainsides covered with snow in winter and edelweiss flowers in summer. But as global heating intensifies, they are increasingly finding an invasive species colonising the slopes: cacti.
Authorities say cactus species belonging to the genus Opuntia, or prickly pears, are proliferating in parts of Valais, encroaching on natural reserves and posing a biodiversity threat.
