Biologists fight giant hogweed

The poisonous, invasive plant from Eurasia can grow 15 feet tall, has spread to 14 states


PIERPONT, Ohio -- Farmer Settilio Codispoti hoped to beef up his three little goats. So he figured the towering, white-flowered weeds that encircled his barn would make great feed.

"The goats got funny," the Italian immigrant said. "No produce milk, no produce kids, no do nothing. So I got rid of 'em."

Now Codispoti knows it was not the goats. He should have annihilated the weeds.

As if Americans don't have enough dangers lurking, here comes the advancing threat of giant hogweed. A public enemy on the federal noxious species list, the alluring weed is doing more than making goats impotent.

It causes burns and bubbly blisters on legs and arms of people who come into contact with its sappy juice. It leaves folks crazed with itching. Discoloration on the skin can last a year.

Hogweed, a renegade of the carrot family, has surfaced in Michigan, Indiana and Wisconsin. When a botanist found a patch near Warsaw, Ind., in 2004, state natural resources crews went on high alert. In a fury, they literally obliterated the plants with shovels and chemicals.

"We made a stand and got really aggressive with this beast," said Glenn Nice, a weed scientist at Purdue University. "It's a real pest, and we don't want it here."

Known to botanists as Heracleum mantegazzianum, hogweed has centuries-old roots in the mountains of Eurasia. But it looks like something out of a rain forest.

Hogweed can grow twice as tall as a professional basketball center - 15 feet. Its hollow stem is as big around as a household water pipe and is accented by purple-reddish blotches.

The weed produces a flat oval fruit that Iranians have long used as an anise-tasting cooking spice called golmar. In a usual summer season, flowers from one hogweed plant produce 10,000 to 20,000 seeds that often spread by water.

To this day, hogweed remains a royal pain in Britain. In Europe it is known as the "giant alien."

In London, hogweed threatens to hog-tie construction for the 2012 Summer Olympics. Thousands of the weeds are choking sites planned for several competitions. The weeds will have to be chopped and burned to prevent their spread.

In North America, hogweed drew notice in the early 1900s in an upstate New York arboretum. Rich tourists seeking to spruce up their gardens likely carried it there from Britain, experts said.

"It was praised as a beautiful exotic plant and highly admired," said Melissa Bravo, a state weed scientist in Pennsylvania who keeps tabs on hogweed infestations.

Today, even though it's against the law to transport and "propagate" hogweed, federal agriculture officials suspect ornamentalists - their term for gardeners - find the plant irresistible and carry it across state lines. That makes the spread of hogweed difficult to chart and predict.

"People see it and go `ahhh' and love to just pick it up and take it home," said David Marrison, an educator with the Ohio State University Extension office in Ashtabula County, Ohio.

Now officials are fighting hogweed on two fronts and in 14 states.

In the Pacific Northwest, hogweed moved south from British Columbia; it has inundated the Seattle area and is moving through Oregon. In the Northeast, hogweed has progressed westward.

Hogweed has overrun rural areas around Erie, Pa., where it spread in the sewer system and has been found in 312 locations. In recent months, sightings have increased in Ohio - alarming residents and state officials. This summer it was found in the Cleveland area.

A national poison-control clearinghouse lists 158 cases of hogweed exposure from 2001 to 2005 - but most incidents are likely unreported, experts said.

E.A. Torriero writes for the Chicago Tribune.

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