Invasive plants have the ability to reproduce quickly and take over an area, whether in the water or on land. These plants typically prevent native species from thriving by crowding them out, keeping sunlight from reaching them and taking needed nutrients from the soil. Invasive plants often are species that escape cultivations and begin to grow in the wild. Florida has its share.
Chinese privet (Ligustrum sinense) grows from Florida's northern counties into those near the Miami area. The shrub is a native plant in China, brought to America around 1852 for ornamental purposes. The species displayed invasive tendencies with its ability to produce huge amounts of seeds and form nearly impenetrable thickets in places such as floodplain forests and open woodlands. Chinese privet grows to about 20 feet tall and is a perennial with 1- to 3-inch oblong leaves. The shrub develops flowers that change into a bluish-black fruit containing as many as four seeds. Birds and mammals will eat the fruit, spreading the seeds through the countryside. Mowing and cutting Chinese privet cannot eradicate it but will slow it down. The manual removal of privet seedlings and control of the species by herbicides helps in the fight against this invasive plant.
Hydrilla (Hydrilla verticillata) is one of Florida's worst invasive plants, affecting waterways throughout the state. Only one species exists of this waterweed, according to the University of Florida Center for Aquatic and Invasive Plants website. Hydrilla can grow in inch-deep water or water as deep as 20 feet. Most of the plant remains submerged, except when it reaches the surface, where it can form a sort of floating mat of leaves and stems. Hydrilla can grow 1 inch in one day and requires just 1 percent of full sunlight to live. This invasive species will slow the flow of water in rivers, clog canals designed for flood control, halt irrigation and interfere with activities such as fishing, boating and swimming. Florida officials attempt to control hydrilla with herbicides, introducing fish and bug species that eat the plant, mechanical harvestors that strip it from the water and by lowering water levels where possible so the weed will die.
The Brazilian pepper-tree (Schinus terebinthifolius) is a relative of poison ivy and poison oak that exists on as much as 700,000 acres in Florida. The tree can attain heights of 30 feet but often is a large shrub. Contact with the Brazilian pepper-tree can precipitate the same dermatitis that its cousins can in sensitive individuals. Native to South America nations such as Brazil and Argentina, the tree came to the Sunshine State as an ornamental in the middle of the 1800s, primarily for the bright reddish berries it produces. The tree grows in the warmest portions of Florida, as far north as Levy County. It will take over in such ecosystems as pine forests and mangrove forests, creating a canopy of branches with leaves so dense that sunlight does not reach other native plants below. The fact that the species can grow in aquatic environments allows flowing water to scatter its seeds, in addition to birds and other animals carrying them to where they may germinate. Herbicides applied to seedlings can control the smaller pepper trees. The entire tree and root system must be removed to effectively prevent it from regenerating. Do not engage in the cultivation and transplanting of this invasive species.