Botanists think they have observed evolution in the act. In fact, botanists - and herbalists and tourists - may be helping evolution along. The Himalayan snow lotus Saussurea laniceps is a rare plant that plays a big role in traditional Tibetan medicine as a treatment for headaches and high blood pressure. Scientists from St Louis, Missouri, have examined herbarium specimens collected 100 years ago, they report in the Proceedings of the National Academy of Sciences, and matched them against specimens collected now. They found that the plant has become shorter.
They then checked a relatively untouched cousin, Saussurea medusa, and found no particular evidence of change. Of the two, S. laniceps was picked more often, with the larger specimens chosen most often. In consequence, the stock of the snow lotus dwarfed rapidly, and even more so in the more heavily harvested areas. They report: "If plants that are smaller have decreased fitness because of lower seed yield then the conservation status of this rare plant may further be threatened by this short-term evolutionary change."
