It’s often said that plants hidden in the tangle of the Amazonian rain forest may harbor an undiscovered cancer cure. John Richa

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问题     It’s often said that plants hidden in the tangle of the Amazonian rain forest may harbor an undiscovered cancer cure. John Richard Stepp thinks the same can be said for the world’s weeds.
    In a study published last year, Stepp, a professor at the University of Florida in Gainesville, looked at the ingredients of common drugs sold at local pharmacies. Of the 101 primarily plant-based health remedies he examined, Stepp estimated that the main ingredient in about a third of the drags was a weed.
    "Those are Fairly conservative numbers too," he added. "It is actually more than a third. We cut quite a few off the list, because they weren’t quite weedy enough, in my view."
    To be "weedy enough" to meet Stepp’s criteria, plants had to be fast-growing and soft-tissued—unlike trees, for example, which are slow-growing and have woody tissues. Stepp also limited his definition of weeds to plants that thrive in disturbed areas, like farms or clearings, without being deliberately planted.
    Stepp said his tally of common weed-based drags was ten times higher than expected. There are about 8,000 weeds known to science. That figure comprises only about 3 percent of the world’s 250,000 described plants.
    Phyllis Coley is a biologist at the University of Utah who conducts drug-discovery research in the Panamanian tropical rain forests. She said Stepp’s finding is "provocative."
    Coley noted that weedy plants have long been a source of traditional medicines. A key question, she said, is, Why?
    "Perhaps this is because weeds were shown to work better," she said. "But I would also suggest that weedy plants would be much more readily available, as they grow in association with human disturbance and are therefore more likely to be experimented with and developed into medicines."
    Meanwhile Stepp said his 2004 study results suggest that, in addition to exploring the rain forest for medicinal plants, it makes sense to look at the 8,000 or so weeds that grow closer to home.
    The anthropologist doesn’t think drag companies share that view. "The difference between wanting to find new medicines and wanting to find new medicines to make a profit is a very wide gulf," he said.
    Regardless of whether new drugs are developed from weeds, Stepp said weed research could lead governments to respect and promote traditional medicinal practices, especially in parts of the world with limited access to modem health care facilities.
Why are weedy plants a source of traditional medicines according to Coley?

选项 A、They are within human reach.
B、They grow on cultivated ground.
C、They crowd out cultivated plants.
D、They grow profusely where it is not wanted.

答案A

解析 见文章第8段,杂草的生长与人类密切相关,更容易被人类开发成药物。
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