Exotic Plants and Their Effects in Southeastern Florida

Europeans began introducing plants into southeastern Florida during the 16th century, and by the middle of the 18th century several of these were already naturalized. Few of these events have been recorded, but we know that the Guava, Papaya, and oranges, were among the early immigrants. American settlement in the middle 1800s began another phase of plant movement which continues to the present. H. M. Flagler, Henry Nehrling, John C. Gifford, and others, brought plants in for landscaping or other uses. Among those brought in by the United States Department of Agriculture were the Sisal, introduced by Henry Perrine, and the many food and ornamental plants sent by David Fairchild to the Miami Introduction Station. Many of the plants brought to Florida have become important as ornamentals or foods; however, some of the exotics have escaped and now present problems to the native ecosystems and to Man.Over 170 species of ferns and flowering plants are naturalized in southeastern Florida. Hundreds of other exotic plants have been introduced into the region and the potential exists for others to escape. Species such as Melaleuca quinquenervia are invading wet habitats and decreasing diversity; the Australian Pine (Casuarina equisetifolia) has become so abundant on some beaches that it interferes with nesting seaturtles and American Crocodiles, as well as contributing to dune erosion. Water-hyacinth (Eichhornia crassipes) and Florida Elodea (Hydrilla verticillata) clog natural and artificial lakes, ponds, and canals, blocking boat traffic and slowing water movement. Several grasses that were introduced as pasture plants are now considered pests. Even human health is being threatened by exotic plants such as the Melaleuca and Pepper-tree (Schinus terebinthifolius), which cause respiratory allergies and contact dermatitis.