Native Plant Fights Back Against Invasive Species

By: Ann Northrup

Ann Northrup spent her undergraduate years at the University of Michigan, where she earned a Bachelor of Science in microbiology….

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Evidence from research done in Georgia demonstrates the North American native clearweed (Pilea pumila) gains a degree of resistance over time to the allelopathic warfare of Eurasian invasive garlic mustard (Alliaria petiolata). The chemical weapon used by garlic mustard, sinigrin, is relatively novel in North America, giving the mustard a competitive advantage over native plants. Sinigrin is directly detrimental to the growth of plants, and perhaps also to the beneficial soil fungi that plants depend upon. In the presence of a greater density of native plants, garlic mustard pumps out a greater quantity of sinigrin. Clearweed growing in the presence of aggressively toxic garlic mustard appears to develop resistance to sinigrin. Unexpectedly, its resistance to sinigrin makes clearweed less fit in the absence of garlic mustard, as determined by transplant experiments. Results of the experiments give hope to the idea that invading allelopathic species can over time, be integrated into native communities without causing great damage. Humans might also play a part. Typically, when invasives are removed and replanted with natives, the natives often fail. If the natives used for replacement come from an area already challenged by the invasive species, greater success might be expected.

PNAS 2012 109 (28) 11240-11245