Allelopathy Journal

Many exotic plant species undergo astounding increases in dominance when introduced to new communities by humans. This is primarily attributed to escape from specialist consumers. However, strong allelopathic effects by some powerful invaders and much stronger allelopathic effects in invaded ranges compared with native ranges suggest a new theory for invasive success – the novel weapons hypothesis. Here we discuss the evidence for allelopathic effects of Centaurea maculosa and C. diffusa and propose that some invaders transmogrify because they possess novel biochemical weapons that function as unusually powerful allelopathic agents or as mediators of new plant-soil microbial interactions. Novel biochemical weapons possessed by some plant invaders may provide an advantage based on historical coevolutionary trajectories.