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Column One: Carnivorous plants losing ground in the U.S.

Scientists are on the trail of the little-understood meat-eaters like the California cobra lily and Venus' flytrap, in decline amid rampant poaching and other human encroachment.

September 07, 2010|By Amina Khan, Los Angeles Times

Reporting from Quincy, Calif. — — "This is the easy part," says Barry Rice, half-sliding, half-falling down a ravine through a latticework of dead branches.

Decades ago, lush stands of Darlingtonia californica — emerald plants coiled like fanged cobras ready to pounce — grew at this spot in the northern reaches of the Sierra Nevada.

Deep in the ravine, the air is hot and dead. Pieces of bark that have sloughed off trees make every step a danger — nature's equivalent of a thousand forgotten skateboards cluttering a driveway. Slate tinkles underfoot, and the ground feels like stale angel-food cake: stiff yet porous.

Rice, a botanist at UC Davis, is not the first to hunt the cobra lily here in Butterfly Valley. In 1875, amateur botanist Rebecca Austin fed the plants raw mutton and carefully observed how they digested it.

Yet to this day, much of the plants' biology and habitat remain unknown — which is why Rice is here, trying to find established populations.

Near the bottom of the crevice, the ground becomes moist. The air cools and softens. This is where the cobra lilies would be. "When you see them, they look almost like animals," Rice says.

But there are none to be seen.

Rice does find meat-eaters in some of the other places he checks out on this July weekend. But in three of seven places where they used to be, the plants have vanished. It's a sad story that is playing out across the country in the valleys, bogs and bottoms where carnivorous plants once thrived.

The cobra lily, also known as the California pitcher plant, is comparatively lucky: Its stocks may be dwindling but its broad habitat affords something of a safety net.

Many of its brethren are faring far worse: insect-devouring butterworts, bladderworts, sundews, other pitcher plants and most famous of all, the Venus' flytrap. The bulk of their U.S. habitat has disappeared, especially in the Southeast, mostly because of human encroachment of various kinds: development, poaching and suppression of naturally occurring wildfires.

Woodland fires remove taller foliage that keeps the stubby meat-eaters from getting enough sunlight. But because of development, allowing fires to burn in their habitats is often out of the question.

In California, alders have grown tall enough in some places to shade out the cobra lily.

In Georgia, botanists have hacked through thickening Appalachian forest in an effort to save the state's last remaining colony of mountain purple pitcher plants.

In North Carolina, of about 250 Venus' flytrap sites that existed in the 1930s, about two-thirds are left and just 32 have a good shot at survival, said Rob Evans, coordinator of the North Carolina Plant Conservation Program.

What plants remain are often plucked from swamps and bogs by poachers and hawked at roadside stands, farmers markets, nurseries or on the Internet.

"I remember visiting [one site] for the first time 30 years ago and there were probably 50 acres where you couldn't take a step without there being a flytrap, and 30 years later, not a flytrap to be found," said Johnny Randall, assistant director for conservation at the North Carolina Botanical Garden. "Literally hundreds of flytraps had been poached out of there."

They possess a notable trait bequeathed by as much as 125 million years of evolution: the ability to capture and digest insects (and reputedly rats, in the case of Nepenthes rajah of Borneo, which can grow more than 3 feet high). Because they draw nutrients such as nitrogen from the carcasses of bugs instead of relying on their roots to extract minerals from the ground, they can live in the poor-quality soil found in bogs.

Most meat-eating plants passively trap their prey, relying on a bug's clumsiness or carelessness. Sundews exude a sticky substance that traps insects; the many varieties of pitcher plant just wait for bugs to fall into their vases.

Some, like the cobra lily, have downward-pointing hairs to prevent insects from climbing out, and transparent patches on their leaves to trick bugs into heading for false exits.

The Venus' flytrap is one of the few that actively traps its prey. When an unsuspecting fly, lured by scent, lands on a trigger vein in the leaf, the leaf snaps shut like a jaw, caging the victim with sawtooth-like spines.

Carl Linnaeus, known as the father of modern taxonomy, at first dismissed reports of the plant, convinced that such a thing could not exist. Charles Darwin, in his little-known work "Insectivorous Plants," said that of all plants, the Venus' flytrap was "one of the most wonderful in the world."

Its native habitat is limited to a few parts of North and South Carolina, where by some estimates there are as few as 35,800 left. Many more survive "in captivity," flytraps being one of the few carnivorous plants grown for a wider market.

Plants cultivated legally can be purchased in nurseries or the garden sections of hardware stores and supermarkets.

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