Defining the native and naturalised flora for the Australian continent

Abstract

The value of distinguishing between plant species regarded as ‘native’ and ‘alien’ has special relevance in the island continent of Australia, where European settlement was a springboard for human-assisted plant dispersal. The year of European settlement is proposed here as providing a distinction between a ‘native’ and ‘naturalised’ flora and is applied for the entire Australian flora of vascular plants. Herbarium collections and ecological criteria were employed to determine the status of 168 species of ambiguous origin. The date of 1788 proved to be a relatively straightforward criterion to assign native and naturalised status and the origin of only 27 plant species remains ambiguous. The dispersal of plants between continents is an ongoing process but European settlement of the Australian continent represents a very sharp biogeographic event for the Australian flora and provides a straightforward criterion for determining the ‘naturalised’ species.