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Florida's least wanted: invasive plants

Some of them, like fire ants and water hyacinths, have been around so long they seem like a natural part of the landscape. Some, like Burmese pythons, are so big and new they make lurid headlines. And all of them are bad news for Florida's native plants and animals — not to mention the taxpayers. They are the invasives. The exotics. The alien invaders, doing their best to lay waste to the state's ecosystems.

Every year state agencies spend millions of dollars trying to contain these outsider animals and plants, but nothing seems to halt their relentless takeover.

Still, if the state dropped its attempts at resistance, "there would be no stopping them," said Brian Nelson, aquatic plant manager for the Southwest Florida Water Management District. "They pretty much crowd everything else out."

Some invasive species are more dangerous than others. A pet python killed a 2-year-old girl. Coyotes routinely gobble up backyard cats. Some cause a more passive brand of harm: Asian green mollusks clogged the water intake pipes of the Tampa Electric Co. power plant in Apollo Beach as well as the filters of Tampa Bay Water's desalination plant next door.

According to one 1998 study, a quarter of the flora in Florida is made up of non-native exotics. The majority were brought in with the best of intentions as ornamental vegetation, then spread.

One example: the air potato, the runaway bane of Boyd Hill Nature Park in St. Petersburg. It originated from a sample the U.S. Department of Agriculture sent to an Orlando horticulturist in 1905 who later wrote that he had "never seen a more aggressive and dangerous vine in Florida."

Now government is spending more than $100 million a year trying to keep such invasive plants from spreading too far. The amount being spent on the animals is unknown, but it's in the millions as well.

National Invasive Species Awareness Week

Melaleuca: A native of Australia, it's been drying up the Everglades since the early 1900s. And it's as hard to kill as Steven Seagal. Any stress to the trees from fire, cutting or spraying them with herbicide causes millions of seeds to pop out and quickly germinate. Cut the tree down and the stump regenerates. And its flowers and foliage put out odors that can cause asthma-like symptoms, a burning rash, headaches and nausea.

Brazilian peppers: Imported in the 1840s, they look pretty, but can cause an itchy skin rash and the swelling of the face and eyes. Their thickets will quickly crowd out the native oaks, which produce acorns eaten by deer. The deer can't eat the berries the pepper trees produce.

Old World climbing fern: A highly flammable plant, which means it not only shades out native plants but it's a big problem in areas like the Green Swamp. Swamps aren't supposed to burn like the state's pine forests do. If the ferns catch fire, then the ensuing blaze is likely to kill any cypress trees nearby.

Walking catfish: A native of Southeast Asia, it was introduced in one or two places in Florida in the 1960s and within a decade had spread to all of South Florida.

Water hyacinth: Introduced to Florida in the 1880s, it was interfering with enough steamer traffic by 1897 that there were complaints to Congress. It forms dense mats that interfere with navigation, recreation, irrigation and also create good breeding conditions for mosquitoes.

Lionfish: A native of the Indian and Pacific oceans, the fish have recently shown up off the Atlantic coast from Jacksonville to the Keys. They have spines that are poisonous to humans and an appetite that's wreaking havoc among the state's native fisheries.

Australian pines: Once popular as a windbreak planted along the state's beaches, it smothers competing native plants under a heavy blanket of fallen needles and produces a pollen that can cause allergic reactions such as respiratory problems and eye irritation. Meanwhile the roots form an obstruction to sea turtles attempting to lay their eggs in the sand.

For a list of invasive and noxious weeds in Florida, visit

Florida's least wanted: invasive plants 01/10/10 [Last modified: Sunday, January 10, 2010 7:38pm]
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