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Sunday, July 21, 2002

By David Templeton, Post-Gazette Staff Writer

Seldom Seem, David Templeton's whimsical perspective on life and times in and around Washington County, appears weekly in Washington Sunday.

When it comes to invasive weeds, Tom Hart can identify the worst of the local green fiends. In fact, surrounding his attractive South Franklin property full of tall trees and beautiful exotic plants is a veritable weed museum.

This is not by design.

It only proves that weeds are green versions of Napoleon Bonaparte, Genghis Kahn and Julius Caesar rolled into one. They invade by land, sea and air and continue their endless assault until they conquer new territory or meet a strong repellent.

With weed season in full bloom, the retired Washington and Jefferson botanist took time last week to talk weeds and provide a top-eight list of the most invasive ones in Washington County.

His top three are the multiflora rose that shows up more often than a needy relative; the Canada thistle, whose parachuting white seeds look like a cross between the Normandy invasion and a summertime snowfall; and crown vetch -- the same crown vetch growing in highway median strips -- that proves when humankind is your ally, long strips of concrete will not stop your proliferation.

These three backyard bullies are followed on Hart's list by garlic mustard, Japanese knotweed, Japanese honeysuckle, poison hemlock and various shrubby honeysuckles. And Hart hasn't even mentioned the likes of pokeweed, whose sap can penetrate the skin, enter the blood and make people sick, and perhaps the worst weed of all, poison ivy.

But before proceeding with this discussion, I asked Hart to define "weed." He responded with a definition that hit too close to home. "Humans, by definition, are weeds," he said.

Who, me? Dandelion Dave?

"We compete well and get rid of other animals," he said. "We are good competitors. We kill off the competition."

That's exactly what weeds do. They invade. They seize property. They kill competing vegetation. And in some cases, they have thorns and poisons that prompt itching, pain, illness and even death. Consider Socrates, who died from poison hemlock -- No. 7 on Hart's list -- that grows everywhere around us.

Hart is concerned about weeds because his yard is an exotic paradise. He grows day lilies, prairie grasses, three species of bamboo, eye-catching Japanese and Chinese trees and bushes and even a palm tree. "I like weird, different plants," he said, explaining his back yard.

He also has a large pond regularly visited by a blue heron. To his dismay, however, he planted crown vetch on a hillside overlooking the pond to control erosion. Crown vetch is No. 3 on his list.

Weeds, as great generals have shown, know how to surround the enemy and launch a nonstop attack until the opposition weakens and gives ground. Ground is what weeds want. What's frustrating is that people -- the Soil Conservation District, universities, nurseries -- have introduced plants they thought would be useful, like crown vetch, multiflora rose and Japanese honeysuckle, that later proved to be invasive and uncontrollable.

As aggressive as Hart's list of weeds is, he also warns about other noxious, notorious weeds heading our way that could make his list in years to come. Although not a problem yet, mile-a-minute weed and hogweed will reach our woods, back yards and gardens in five to 10 years, he said.

Describing a weed as "mile a minute" is an exaggeration, but not by much. It spreads fast as influenza. Give it an inch, it takes a mile.

"I had some here last year," Hart said. "I saw it and said, 'Oh, my gosh.' I usually don't spray [herbicides], but I sprayed this small weed. It's not big, but it covers ground."

But the most ominous is the huge, toxic hogweed that's heading south from Erie. The only known example of hogweed in Washington County grows next to Hart's back door.

Fifteen years ago, Hart was driving in Erie County with his son and spotted a large, interesting plant he'd never seen before. He eventually returned, collected seeds and planted several around his house without knowing what it was.

Eventually he found out it was toxic, invasive hogweed.

State officials forbid transport or planting of hogweed, whose migration began in Buffalo, N.Y. It invaded Erie County and now is continuing southward.

It grows 15 feet high with a large, hollow bamboo-like stalk and features spiky 5-foot-long leaves. An umbrella-shaped flower produces seeds. It overtakes a property, especially along waterways, and kills everything beneath it.

It also has toxic sap that causes blisters when contaminated flesh is exposed to sunlight.

"I certainly don't expect it to stop spreading," said Bryan Brendley, a Gannon University botanist who studied Erie's hogweed invasion. "The big thing is the burns it causes. I was burned by a plant. It's painful and felt like bee strings and remained sensitive to light for a long time."

Hart does not hide the fact he has hogweed on his property, even though he cuts off the flower before it seeds. He keeps the plant as a showcase example and many, including county officials and botanists from the Carnegie Museum of Natural History, have trooped to Hart's house to see the plant and take pictures of it.

He said cow parsnip often is mistaken for hogweed.

"Personally, I think it's here in the county and will not be stopped," he said. "I would doubt this is the only plant in the county.

"It's important that people know what it is so people can stop it, or make an attempt to stop it. Hogweed and mile-a-minute-weed have such low numbers [in the area], we still have a chance to keep them under control."

It's the only weed Hart keeps on his property willfully.

"If someone tells me to get rid of it, I will get rid of it," he said, admiring his 15-year-old plant. "I think there is value to having one around."

The same is true, I hope, for Dandelion Dave.

David Templeton can be reached by e-mail at: dtempleton@post-gazette.com