Arizona's saguaro cactus has evolved to thrive in the extreme climate of the Sonoran Desert, but after decades of rising heat, even these towering icons are showing signs of stress.

Pink Hill Trail: Saguaro East's wonders . By Doug Kreutz Arizona Daily Star Feb 8, 2009 ... Pink Hill, Loma Verde, Cholla and Cactus Forest trails, for example, totals 3.2 miles.

A crew surveying plants at Saguaro National Park west of Tucson has made a "shocking" discovery: a mature organ-pipe cactus growing among the saguaros.