The health of millions could be at risk because supplies of medicinal plants are being used up. These plants are used to make traditional medicine, including drugs to fight cancer. “The loss of medicinal plants is a quiet disaster,” says Sara Oldfield, secretary general of the NGO Botanic Gardens Conservation International.

    Most people worldwide rely on herbal (药草制的) medicines which are got mostly from wild plants. But some 15,000 of the 50,000 medicinal species are under threat of dying out, according to report from the international conservation group Plantlife. Shortages have been reported in China, India, Kenya, Nepal, Tanzania and Uganda.

    Over-harvesting does the most harm, though pollution and competition from invasive species (入侵物种) and habitat destruction all contribute. Businessmen generally harvest medicinal plants, not caring about sustainability (可持续性),” the Plantlife report says, “damage is serious partly because they have no idea aboutit. but it is mainly because such collection is unorganized” Medicinal trees at risk include the Himalayan yew (紫衫) and the African cherry, which are used to treat some cancers.

    The solution, says the report's author, Alan Hamilton, is to encourage local people to protect these plants. Ten projects studied by Plantlife in India, Pakistan, China, Nepal, Uganda and Kenya showed this method can succeed. In Uganda, the project has kept a sustainable supply of low-cost cancer treatments, and in China a public-run medicinal plant project has been created for the first time.”

    “Improving health, earning an income and keeping cultural traditions are important in encouraging people to protect medicinal plants,” says Hamilton, “You have to pay attention to what people are interested in.”

    Ghillean Prance, the former director of the Royal Botanic Gardens at Kew in London, agrees that medicinal plants are in need of protection. “Not nearly enough is being done,” he told New Scientist. “We are destroying the very plants that are of most use to us.”