Southern African plants naturalized in Australia: a review of weed status and biological control potential.
A literature search revealed that 43 families, 141 genera and 251 species of plants indigenous to southern Africa have become established in Australia, mostly in southern regions. The families with the most species are the Iridaceae, Asteraceae [Compositae] and Poaceae [Gramineae] (20, 15 and 13% of species, resp.). Sixty-eight species are regarded as weeds and 33 species have been serious enough to warrant research expenditure. Problematic weeds of agricultural situations include Arctotheca calendula, Chrysanthemoides moniliferum, Cucumis spp., Emex australis, Eragrostis curvula, Homeria spp., Lycium ferocissimum, Oxalis pes-caprae, Pennisetum macrourum, Romulea rosea, Senecio madagascariensis, Urochloa maximum and Zantedeschia aethiopica. Significant weeds of conservation areas are not well-documented at present, but include Delairea odorata, Ehrharta erecta, Melinis repens, Myrsiphyllum asparagoides, Polygala spp., Protasparagus africanus, Senecio pterophorus and Watsonia spp. Of the southern African weeds not currently the subject of biological control research, Oxalis pes-caprae was identified as having the highest priority. The assessment of the biological and economic importance of Arctotheca calendula and weeds of conservation reserves were identified as research areas requiring attention.