The seeds -- loblolly pine, sycamore, sweetgum, redwood and Douglas fir -- had traveled with Stuart Roosa, one of the three NASA astronauts on the mission and a former US Forest Service parachute firefighter, sealed in small plastic pouches stored in a metal canister in his personal luggage. They were part of an experiment to see how seeds reacted to the space environment. Upon their return to Earth, the seeds were germinated by the Forest Service. Known as the "Moon Trees," the resulting seedlings were planted throughout the United States and the world, according to NASA. There was no systematic...