Mesembryanthemum guerichianum pax (Aizoaceae): a weedy alien species new to Australia.
A newly discovered alien species of Mesembryanthemum, M. guerichianum Pax, is reported for Australia for the first time. It occurs in South Australia, New South Wales and Victoria. It has been overlooked in the past presumably having been mistaken for the widespread M. crystallinum L. which it is closely related to. A detailed account of the species based on Australian populations is given including a description, distribution, ecology, and a brief discussion is provided on current views on the generic limits of Mesembryanthemum. A key to the species of Mesembryanthemum in Australia is provided, and the species is compared with M. crystallinum.