Canada's PM Harper, U.S. President Bush and Mexico's President Calderon plant a tree in honour of Earth Day following the North American Leaders' Summit in New Orleans

Canada's Prime Minister Stephen Harper, U.S. President George W. Bush (C) and Mexico's President Felipe Calderon plant a tree in honour of Earth Day following the North American Leaders' Summit in New Orleans, Louisiana, April 22, 2008. REUTERS/Chris Wattie (UNITED STATES)