A soaring trade in herbal teas and medicines is threatening some plants
with extinction, according to a new study. Eighteen species are in urgent need
of protection, it says, while world sales of herbal potions are increasing by
more than 10 per cent a year, with Britain probably the fastest growing
market.
The findings, from the consulting firm McAlpine, Thorpe and Warrier, which
advises several British importers, are supported by botanists. 鈥淚t鈥檚 a new area
of research, but of great concern,鈥� says Fiona Dennis, who is producing a
separate study on the subject for the World Wide Fund for Nature.
The report鈥檚 main author, Govinda Warrier, says that the endangered medicinal
plants with the largest international markets are Chinese ginseng, 8000 tonnes
of which are traded every year, and Ginkgo biloba or the maidenhair
tree, a fashionable remedy for heart ailments and dementia that is found in
North America, China and Indonesia. Some 2000 tonnes of G. biloba are
sold every year, a third of it in Germany, and this trade is growing by 25 per
cent a year. Other leading products include Harpogophytum procumbens and
Menyanthes trifoliata, both of which fight rheumatism.
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Jim Duke, a former botanist for the US government who advised the McAlpine
study, says that American demand has endangered several South Asian medicinal
plants, including the Indian yew, Taxus vallichiana. 鈥淭he Indian yew
has just been ripped off the hillsides of northern India and Nepal,鈥� says Duke.
Its bark is sold to the US as a recognised treatment for ovarian and other
cancers.
Duke claims that the efficacy of some potions is a myth, and that 鈥渟cience
could help protect several species simply by exposing them鈥�. For instance, the
herb goldenseal (Hydrastis canadensis) has become endangered in the US
鈥減artly because people buy it in the mistaken belief that it masks the presence
of hard drugs such as cocaine in urine analysis鈥�. The plant is also used by
athletes, apparently effectively, to conceal steroids in their urine.
Christine Leon of the Royal Botanic Gardens, Kew, who is investigating the
safety of Chinese medicines for Guy鈥檚 Hospital in London, says that once a plant
becomes rare, suppliers of such medicines often use substitutes in their
products, some of which are unsafe. Leon cites Aquilaria malaccensis,
which is taken as a tonic for stomach upsets and also used as incense. She says
it is being overexploited 鈥渨ith the result that a lot of poor and adulterated
product is reaching the UK now鈥�. Kew is seeking money to establish an
鈥渁uthentication centre鈥� for traditional Chinese herbal medicines.
Dennis points out that trade in herbal medicines is not always bad for the
environment. 鈥淢any plants have been sustainably harvested for a long time,鈥� she
says. One example is witch hazel, made from the bark and leaves of the American
shrub Hamamelis virginiana.
Warrier wants the large trading companies to form a conservation organisation
that would employ scientists to identify threatened species and encourage
cultivation to relieve wild stocks. Cultivation is most developed in Germany,
the world鈥檚 largest market for herbal products with a trade worth more than
拢1.4 billion a year.
However, Duke warns that consumers sometimes prefer wild versions. Wild
ginseng, for example, produces a wiry root which is very popular, while 鈥渢he
cultivated version looks more like a carrot鈥�.