Amazon hosted a ceremonial tree planting Thursday as work continued on the large glass domes at the center of the company's downtown Seattle campus. The Australian tree fern is the first plant to call the spheres home. The spheres will house a kind of indoor park for Amazon employees with hundreds of different species of plants from around the world. "This is an opportunity to link nature to today's office space," said John Schoettler, Amazon's vice president of global real estate and facilities