How long can a saguaro cactus live to be?

Question

How long can a saguaro cactus live to be?

Answer 1

The Saguaro, pronounced "sah-wah-roh", (Carnegiea gigantea) is a large, tree-sized cactus species in the monotypic genus Carnegiea. It is native to the Sonoran Desert in Arizona, the Mexican states of Sonora and Baja California, and an extremely small area of California. The saguaro blossom is the state flower of Arizona.

Saguaros have a relatively long life span. They take up to 75 years to develop a side arm. The arms themselves are grown to increase the plants reproductive capacity (more apices equal more flowers and fruit). The growth rate of saguaros is strongly dependent on local precipitation patterns, and saguaros in drier western Arizona grow only half as fast as those in and around Tucson, Arizona (Drezner, 2003). Some specimens may live for more than 150 years;the champion saguaro grows in Maricopa County, Arizona and is 13.8 meters (45.3 ft) tall with a girth of 3.1 meters (10 ft). (It was injured as a result of the Cave Creek Complex fire in June 2005.) In addition to being slow growing, they are also slow to propagate. Harming one in any manner (including cactus plugging) is illegal by state law in Arizona, and when houses or highways are built, special permits must be obtained to move or destroy any saguaro affected.

The spines on smaller saguaro (having a height less than 2 meters or 6 feet) grow rapidly, up to a millimeter per day. When held up to the light or bisected, alternating light and dark bands transverse to the long axis of spines can be seen. These "transverse bands" have been correlated to daily growth (one light/dark couplet equals one day of growth). In columnar cacti, spines almost always grow from the apex of the plant and then cease to grow as they are moved to the side and the apex continues to grow upwards. Thus, the older spines are towards the base of a columnar cactus and newer spines are near the apex. Current studies are underway to examine the relationship of carbon and isotope ratios in the tissues of spines to the past climate and photosynthetic history of the plant

Answer 2

100 years

Answer 3

The Saguaro often begins life in the shelter of a "nurse" tree or shrub which can provide a shaded, moister habitat for the germination of life. The Saguaro grows very slowly -- perhaps an inch a year -- but to a great height, 15 to 50 feet. The largest plants, with more than 5 arms, are estimated to be 200 years old. An average old Saguaro would have 5 arms and be about 30 feet tall.