Saguaro National Monument consists of 2 districts, Saguaro West and Saguaro East. Together Saguaro West and the much larger Saguaro East preserve 87,114 acres of the life and landscape of the Sonoro Desert, including the park’s namesake, the saguaro.
The saguaro has been described as the monarch of the Sonoran desert, as a prickly horror, as the supreme symbol of the American Southwest, and as a plat with personality. It is renowned for the variety of odd, all-too-human shapes it assumes, shapes that inspire wild and fanciful imaginings. Since 1933 this extraordinary giant cactus has been protected within Saguaro National Monument. Preserved along with it are many other members of the Sonora desert community -- the other cacti, the desert trees and shrubs, and the animals In lushness and variety, the Sonora Desert far surpasses all other North American deserts. Summer midday temperatures quite commanly climb above 100o F. Less than 12 inches of rain fall in a typical year.
The saguaro begins its life as a shiny black seed no bigger than a period. One saguaro produces tens of thousands of seeds in a year, and as many as 40 million in a lifetime of 175 to 200 years. From the start, the odds against survival are great. Out of all the seeds that a saguaro produces in its life, probably only one will survive to adulthood.
A saguaro’s growth is extremely slow. Growth occurs in spurts, with most of it taking place in the summer rainy season each year. By the end of a year the saguaro seedling may measure only 1/4 inch. after 15 years, the saguaro may be barely a foot tall. At about 30 years saguaros begin to flower and produce fruit. By 50 years the saguaro can be as tall as 7 feet. After about 75 years it may sprout its first branches, or "arms."
-- Text from USNPS brochure --