Arctotheca calendula (L.) Levyns (Asteraceae): an emerging invasive alien species in Iran

The herb Arctotheca calendula (capeweed) is reported as a new record for Iran. A detailed description, a distribution map, colour photographs of an herbarium sample, and diagnostic features are provided to facilitate identification. The species was first observed in 2017 in the Miankaleh Biosphere Reserve, one of the thirteen UNESCO Biosphere Reserves in Iran. Since 2017, the A. calendula population has been thriving and locally expanding. As capeweed is generally described as an invasive species with negative impacts, having both high reproductive potential and highly mobile propagules, we suggest prioritizing an eradication intervention for this alien weed before it becomes too widespread.