Desert Ironwood (Olneya tesota) and Saguaro cacti (Carnegiea gigantea) are currently in bloom west of Tucson. A good place to see them is along Picture Rocks Road through Ironwood Forest in Saguaro National Park. Desert Ironwood trees have numerous, small, light purple flowers, while Saguaro cacti have crowns of large, white flowers.
Saguaros can often be found growing under "nurse trees" like Desert Ironwoods because very young Saguaros require some shade and protection. Eventually, the long-lived Saguaro will outlive the nurse tree and be found growing alone.
Desert Ironwood trees have extremely dense, hard wood that sinks in water, and this iron-like wood is still used by some Native Americans to make attractive and durable, carved objects.