These invasive nonnative plants have such a devastating effect because their natural controls are missing and some can establish dominance in the absence of predators. Aggressive invaders displace native species that may provide food and habitat for native animals. Foreign species were intentionally introduced in the past with noble intentions. Florida is a particularly instructive example having played willing host to hydrilla which now infests over 75,000 acres of the state's waterways. Melaleuca, now a major threat to the Everglades, was introduced in 1906 as an agricultural windbreak, soil stabilizer and ornamental tree.
Australian pine overruns the barrier islands endangering sea turtle and American crocodile habitats.
Many of these dangerous plants are commercially available today in Florida and elsewhere. Our globalized economy is part of the problem with greater personal travel and increased cross-border commerce. The problem is so threatening an all-out federal interagency government effort has been launched to not only research and combat the invasion but to educate the public and enlist cooperation of the states. Of the thousands of alien plants introduced to the U.S. fourteen hundred have been identified as pests and of that number, ninety-four are recognized as noxious weeds. These invasive exotics can have far-reaching impact on croplands, forests, parks, preserves, wilderness areas, wildlife refuges and urban parklands.