New records of alien vascular plants from Marion and Prince Edward Islands, sub-Antarctic
A survey was made of the distribution of introduced vascular plants on Marion and Prince Edward Islands. The results of this survey were compared to results of previous surveys (1965/66, 1975, 1981, 1989). Four new introductions to Marion Island have taken place, three of which involved species that had been introduced in the past, but had disappeared or were eradicated. Eighteen species of alien vascular plants are now known from Marion Island. Of these, three were not observed during the present survey, and another three have been eradicated. Many of the naturalised aliens are still increasing markedly in area and/or in numbers. Rates of spread of up to 300 m year-1 occur. Three alien vascular species occur on Prince Edward Island. Two are recent introductions, presumably transported to this island from neighbouring Marion Island by wind or birds.