BRISBANE, AUSTRALIA - APRIL 19:  Catherine, Duchess of Cambridge plants a tree with her husband Prince William, Duke of Cambridge at the RAAF Amberley airbase on April 19, 2014 in Brisbane, Australia. The Duke and Duchess of Cambridge are on a three-week tour of Australia and New Zealand, the first official trip overseas with their son, Prince George of Cambridge. (Photo by Phil Noble - WPA Pool/Getty Images)