Results/Conclusions Invasiveness and novelty both affected species performance: novel, highly invasive species are larger than less novel highly invasive species. However, novel noninvasive species are smaller than less novel noninvasive species, which suggests that there are costs, as well as benefits, to being novel. Species differed in their response to competition and herbivory removals: some species showed herbivore escape and/or competitor resistance. There is evidence that the novel species experience greater herbivory escape and have greater competitive ability than less novel species, suggesting that these two mechanisms might drive a benefit for more novel species. There was also some evidence for the presence of water-soluble allelochemicals in the leaf tissue of several species, potentially driving the greater competitive ability of more novel species.