Cotula alpina (Asteraceae) naturalised in the British Isles

Abstract

Cotula alpina (Hook f.) Hook f. is an Australian herb that has been naturalised in Britain since the 1970s and is now locally abundant in parts of northern England and northwest Scotland. Its method of arrival is unknown but it is likely to have originated from gardens and perhaps also from wool shoddy. It appears to be spreading rapidly due to high seed production and effective dispersal by sheep, humans and vehicles and is now locally abundant on moorland tracks and in adjacent acid grassland and heather moorland managed for grouse. Due to its evergreen and mat-forming habit it can outcompete community dominants such as Agrostis capillaris and Festuca ovina in areas where levels of grazing are high. It appears to be well suited to the British climate and is therefore likely to spread into similar habitats in other regions where it could pose a threat to localized species associated with short grassland on acidic soils. Its overall abundance and ability to regenerate rapidly from seed means it is unlikely to be easily controlled or eradicated, although exclusion of grazing may help to reduce its abundance in some areas.