This feb. 28, 2013 photo shows a clematis flower at Raymond Evison's installation during preparations for the annual Philadelphia Flower Show at the Pennsylvania Convention Center, Thur

 

              This feb. 28, 2013 photo shows a clematis flower at Raymond Evison
This feb. 28, 2013 photo shows a clematis flower at Raymond Evison's installation during preparations for the annual Philadelphia Flower Show at the Pennsylvania Convention Center, Thursday, Feb. 28, 2013, in Philadelphia. More than 270,000 people are expected to converge on the Pennsylvania Convention Center for the event, which runs through March 10. Billed as the world's largest indoor flower show, it's also one of the oldest, dating back to 1829. (AP Photo/Matt Rourke)