ABSTRACT
Some cosmopolitan species may be regarded as either alien or native.4-6 For Australia as a whole, it was estimated3 that this uncertain status applies to only 34 plant species, that is, 1.1%, which is a small proportion of the total alien ®ora. These relatively few plant species typically occupy either wetlands or beach strandlines, where bird-or water-dispersed species predominate. Although these cosmopolitan species may be numerically signi¢cant among most insular ®oras, including those of Australian islands, they comprise only a trivial proportion of the ®ora of the large land mass of continental Australia.
