by Alex Gugel , all rights reserved
Organ Pipe Cactus
Growth of a Saguaro Cactus
National Park Service U.S. Department of the Interior Organ Pipe Cactus Organ Pipe Cactus National Monument Saguaro Cactus One Inch tall 10 years One Foot tall 30 years 3 Feet tall 50 years First Flowers 6 1/2 feet tall 70 years First Arm 15–16 feet tall 95–100 years Full height 43 feet 200 years Age based upon average annual growth within the monument. A single saguaro cactus (Carnegiea gigantea) can produce millions of seeds in its lifetime (estimated 20–40 Millions). Only a few of these seeds actually sprout. Even fewer grow to maturity. The most successful cactus begins its growth under the shade of a larger plant, commonly called a nurse plant. Almost any plant can become a nurse plant. Shade from the nurse plant protects the delicate cactus seedling from temperature extremes and How Old Is It? sunburn. Shaded soil holds moisture longer. Slowly decaying leaf litter adds nutrients. Leaf litter hides the tender young plant from hungry birds or animals seeking a juicy bite of salad. The saguaro cactus seedling grows best in this protected, humid environment and enriched soil beneath its nurse plant. It grows very, very slowly. No one knows for certain. Estimating the age of a cactus is difficult. There are no annual growth rings, as there are in trees. Rainfall, soil conditions and exposure to sunlight all influence the rate of growth for a saguaro cacti. Long-term scientific studies plus photographic records and other data aid researchers in estimating the age of saguaro cactus. The data used here was determined from saguaro growing at the mouth of Alamo Canyon within the monument. Age and height relationships will vary in other parts of the Monument and in other parts of the Sonoran Desert. For instance, in a wetter environment such as that on the east side of Saguaro National Park in Tucson, growth rate is faster. A cactus one inch tall may be only six years old. It may reach a full height of 46 feet in merely 173 years. All data from studies by Warren F. Steenbergh and Charles H. Lowe, Ecology of the Saguaro: III. Growth and Demography. NPS Scientific Monograph Series 17, 1983 EXPERIENCE YOUR AMERICA © CREDIT 2015 - ALL RIGHTS RESERVED. How Does It Grow?