- WASHINGTON -- St. John's wort and other medicinal herbs may be great for
what ails you, but they can be hell on the environment.
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- The growing popularity of these plants,
many of which are not native to the areas they grow in -- or even to the
United States -- has led to their spread across the countryside, where
they have crowded out native plant species and driven some toward extinction.
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- St. John's wort and other herbal plants
can spread from the farms where they're cultivated, if growers aren't careful
about when and how they harvest them.
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- "If people want to start planting
hundreds of acres of klamath weed, and do not keep the plant from staying
in the growing areas and let it go to seed, the plant will just spread
from its growing area," said Nate Dechoretz of the California Department
of Food and Agriculture.
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- "For many years, St. John's wort
was a major pest to agriculture in California," he said. "Bio-control
agents have been developed and released and established that resulted in
pretty darn good control."
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- Now heavily marketed as a natural anti-depressant,
St. John's wort is in some places considered a noxious weed.
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- In Ventura County, Calif., for example,
St. John's wort -- also known as hypericum and klamath weed -- grows wild
throughout the county, choking out native plant species. State, county
and federal agriculture departments have introduced beetles and moths into
the ecosystem to reduce the prevalence of the weed.
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- When Rick White of the U.S. Agriculture
Department's Natural Resource Conservation Service found out St. John's
wort was being marketed as an herbal medicine, "it sort of surprised
me," he said, "because St. John's wort in general is considered
a poisonous plant to livestock. It was introduced into the United States
(from Europe), particularly the northwest portion of the country, and became
quite a problem, invading plant communities and so forth."
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- St. John's wort grows wild throughout
much of the United States and Canada.
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- In California, when a farmer wants to
plant it, the state Food and Agriculture Department refers the request
to the agriculture commissioner in the farmer's home county.
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- "This is a matter of concern to
many counties and many will decline the request," Dechoretz said.
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- Other popular herbs that various state
agriculture departments list as noxious weeds include:
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- -- Milk thistle, used for liver disorders.
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- -- Common burdock, advertised as a blood
purifier, a treatment for skin diseases and a weight-loss supplement. In
addition to choking out native plant species, burdock "is a very serious
threat to sheep as the burs can significantly damage the quality of the
wool," the Colorado Weed Management Association reports.
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- --Wild fennel, used to relieve gas and
acid stomach, is on California's list of "most invasive wildland pests."
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- -- Yellow toadflax, introduced from Europe,
is now "a serious problem to rangeland and mountain meadows,"
according to the Colorado Weed Management Association.
-
- -- Foxglove, a source of the heart stimulant
digitalis, is an "escapee from cultivation" that grows in "disturbed"
areas, such as clear-cuts, said William Gregg, invasive-species coordinator
for the U.S. Geological Survey.
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- "It's an extremely attractive plant
and, unfortunately, some of our worst invaders were brought over here because
they had horticultural properties that people really liked," he said.
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- Invasive herbs needn't be a problem as
long as herb growers harvest their plants before they go to seed, Tim Blakley
of the National Center for the Preservation of Medicinal Herbs told National
Food Merchandiser, a trade magazine.
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- "Quality growers harvest before
the plant goes to seed anyway," he said.
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