The saguaro is a large, tree-sized cactus species which can grow to be over 70 ft tall. It is native to the Sonoran Desert in the U.S. state of Arizona. The saguaro blossom is the State Wildflower of Arizona. The saguaro cactus shown in the picture are along US 93 in Mohave County Arizona.

Saguaros have a relatively long life span. They take up to 75 years to develop a side arm. A saguaro without arms is called a spear.

The arms are grown to increase the plant's reproductive capacity. The growth rate of saguaros is strongly dependent on precipitation; saguaros in drier western Arizona grow only half as fast as those in and around Tucson, Arizona.

Some specimens may live for more than 150 years, the largest known saguaro is the Champion Saguaro. It grows in Maricopa County, Arizona, and is 45.3 ft tall with a girth of 10 feet. These cacti can grow anywhere from 40 to 60 feet.

They grow slowly from seed, and never from cuttings. Whenever it rains, saguaros soak up the rainwater. The cactus will visibly expand, holding in the rainwater. It conserves the water and slowly consumes it.