According to the novel weapons hypothesis allelopathy may facilitate invasions of exotic plants especially if the newcomer's biologically active compounds meet nonadaptated native species (Callaway and Ridenour 2004). Heracleum mantegazzianum (giant hogweed) is one out of ten most troublesome invasives in Europe, drastically reducing the biodiversity and through its sap containing photodermatitic furocoumarins being dangerous even to animals and people.
Surprisingly, the role of allelopathy in its invasion has been overlooked so far.