Aliens

Water hyacinth is a well known aquatic weed; less well known but almost as bad is alligator weed (Alternanthera philoxeroides of family Amaranthaceae). It originated from South America, but was introduced to North America as an ornamental (and as crayfish fodder), and is now considered an invasive species not only there but also in Australia, China, New Zealand, and Thailand (it is even naturalized in Italy). Succesfull attempts to controll the alligator weed have been made by introduced insects.

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