After one of his famous walks, the bearded naturalist John Muir wrote in 1896, »Few are altogether deaf to the preaching of pine trees.« But if today’s trees could tell their stories, some American branches would be whispering new tales of origin: epics of genetic engineering in 150 groves from Puget Sound to the palmetto flats of South Carolina. Scientists are increasingly tweaking the genetics of trees in the laboratory to enable them to do such things as live at higher altitudes, produce more fruit, convert more easily into pulp for paper products, and grow faster for timber harvesting.