The Genetic and Morphological comparison of a potentially invasive weed (Argemone ochroleuca) from its' natural (North America) and invaded (South Africa) habitat.

Morphological and genetic comparisons of a potentially invasive weed (Argemone ochroleuca) from its’ natural (North America) and invaded (South Africa) habitats are presented. Seeds from 13 North American and 13 South African populations were germinated and established in common garden conditions. A variety of morphological and genetic attributes were examined to a) determine if invasion success for this species is reflected in attributes such as seed size; germination rate; growth rate, defence etc and b) if the background variation in morphology and genetics is significantly different between the two groups (natural vs. invaded range). Compared to natural populations, seeds in invaded populations were significantly less variable in size and germinated more consistently, even when taking into account seasonal variance associated with hemisphere of origin. In addition, thorns, specifically on seed capsules, significantly better defended adult plants. Genetic data substantiate the diversity in the native populations. All the South African populations are identical, with one exception; one North American population identical to the South African populations, therefore possibly the origin populations for the South African populations.