Complex sentence: The park was established to protect its namesakethe giant saguaro cactus ("Carnegiea gigantea"), which at this latitude are near the northernmost limit of their natural survival zone within the Sonoran Desert.
Split into simpler sentences: The park was established to protect its namesakethe giant saguaro cactus ("Carnegiea gigantea"). Saguaro in this park are near the northernmost limit of their natural survival zone within the Sonoran Desert.