Acacia longifolia, a species of acacia from the Fabacean family that is native to Australia, was initially cultivated in Portugal as a means of securing sand dunes and is now spreading uncontrollably -- with varying impact on native species. Since the plant can use nitrogen from the air on account of its symbiotic relationship with bacteria on its roots, and since it also grows rapidly and produces a lot of biomass, it enriches the naturally nutrient-poor dune ecosystem with nitrogen, leading to an undesirable fertilization effect.