Old world climbing fern, lygodium microphyllum, is a double threat. It is an invasive, capable of smothering trees and shrubs and choking out native orchids, bromeliads and a host of understory plants. It can swallow tree islands whole, figuratively speaking. But what makes this plant especially dangerous is fire. This fern can act as a ladder that enables brush fires to reach the upper canopies of forests.

Old World is found in swamps, wetlands, wet meadows and hammocks of Florida's peninsula from Brevard and Hillsborough counties southward. As you might guess, it is a major ecological threat anywhere it's found — only in Florida now, but Texas and Louisiana are believed to be vulnerable as are the Caribbean, Central Ameria and South America. It is listed as a noxious weed in Alabama, Florida and by the federal government.

It is a native of Africa, Southeast Asia, Australia and the South Pacific, and came to this country as an ornamental. By 1960, naturalists found the first specimens of old world growing in the wild. The Institute for Regional Conservation believes it is being cultivated still.

It spreads three ways — by rhizomes, or stems that grow along the ground or just under it; by spores; and by its climbing leaves, which can resprout when clipped from the main plant. It produces spores by the zillions, which can be distributed many, many miles by the wind, particularly during storms, by animals and by humans when the spores attach themselves to clothing and equipment. It produces spores year round, but peaks during the fall — September to November.