Like the insatiable plant from the musical "Little Shop of Horrors," a verdant menace is eating the Everglades.

The Old World climbing fern, known to botanists as "Lygodium microphyllum," spreads its asphyxiating fronds like fingers around the necks of native cypress and mangroves. It smothers the flora of the glades' unique tree islands and starves out the endangered wood storks and other fauna.

"You can't cut it because it grows right back. You can't burn it without harming what it covers. You can't kill it with water because it survives varying hydrologies," said Bill Miller, a U.S. Fish and Wildlife Service biologist.

And, Miller laments, "Nothing in the Everglades feeds on lygodium."

The Old World climbing fern and other invasive plants now cover more than 2 million acres of the Everglades, including 70 percent of this national refuge and ever-expanding stretches of Everglades National Park, Big Cypress National Preserve and the Seminole and Miccosukee reservations. When environmentalists talk about invasive species in the Everglades, they often are referring to Nile monitor lizards, 350-pound Komodo dragons from Indonesia or the Burmese pythons abandoned there by humans. The pythons are now challenging alligators for supremacy in the swamp.

The rapacious fern, which originated in Australia, doesn't grab attention in quite the same way.

But biologists and conservationists contend the non-native plants pose a greater risk to survival of the Everglades, half of which has disappeared after a century of bulldozing and dredging.

Scientists also warn that efforts to contain and eventually eradicate alien plants increasingly will challenge federal, state and local budgets, which are struggling to ante up their shares of the $8 billion committed through the Comprehensive Everglades Restoration Plan.

The Everglades is a natural resource that has been hard to love. Its malodorous, sweltering bogs are a sanctuary more for creatures that bite, sting and slither than for humans. But as a shelter for rare birds, flowers and animals, conservationists dating to Florida settlers have fought to preserve it.

The 2000 Everglades restoration project is aimed at correcting the engineering and development intrusions that have reduced wading bird populations by 95 percent, endangered 68 plant and animal species, and cut water flow through the glades by 70 percent.

It would refill canals, restore the natural flow of rivers, and cease mining and other industry encroaching on protected areas. It also would relocate some farming communities established during the early 20th century that now require water diversions and electricity in the government-protected refuges and release polluted irrigation water into the everglades' re-engineered flow.

But the nation's biggest environmental repair project ever pays little heed to the problem of invasive species, which nature defenders warn could nullify the results of spending $8 billion to clean and re-plumb the national treasure.

If left untreated, lygodium will cover an area of South Florida larger than the entire Everglades National Park within seven years, according to a computer-generated projection by Florida Atlantic University biology professor John Volin.

His forecast is based on aerial surveys of the Everglades made since 1976, when lygodium first popped up on the pest plant radar in the glades northeast of Lake Okeechobee.

Lygodium was brought to Florida in the 1950s by gardening clubs impressed with its prolific speed in ornamenting fences, posts and trellises. Winds wafting over the plant shake loose its copious pods, releasing lygodium seeds that are carried into virgin lands.

The melaleuca tree, another nemesis, was imported a century ago when Florida's white settlers considered the Everglades a useless swamp that should be drained for crop production. The Australian-native tree was renowned for its water consumption and planted among the tree islands to suck the wetlands dry.

While people working to protect and restore the Everglades can cite progress in reducing some invasives, like the melaleuca, the Australian pine and Brazilian pepper, tackling lygodium is a Sisyphean effort.

Each leaf of the fern is hemmed with pods that disperse their seeds to the winds, even when the fern is being burned, removed by hand or chemically treated. And it is spreading about 10 times faster than it is being destroyed.

Each day, as many as 30 contractors and wildlife experts are at work trying to eradicate the invasive plants in the Loxahatchee refuge alone.

Mike Page, a veteran helicopter pilot flying for the South Florida Water Management District, deploys half a dozen choppers with spraying booms over the infested tree islands to apply herbicide to lygodium and melaleuca.

It is a precision operation begun this spring and costing the state as much as $300 per acre. By May 1, Page's team had covered 8,000 acres - less than 10 percent of the invaded areas of the 143,000-acre refuge.

Two weeks after the spraying, laborers usually can approach the tree islands on airboats to remove the browned and desiccated plant scraps manually. But a drought this spring has marooned many of the invaded areas, preventing collection of the foliage that is now dead but still smothering native vegetation.

"The goal now is control. Eradication is a long time coming," Miller conceded.

Dumping foreign species of any kind, plant or animal is illegal in Florida but it is far from uncommon.

With the Everglades' thousands of miles of canals and millions of acres of remote territory, the risk of detection is minimal and the paths of encroachment long, vast and defenseless.