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Saguaros Giant Cactus Sentinels of the Sonoran Desert
Symbol of Southern Arizona
The carnegiea gigantea or giant saguaro cactus is the symbol of the state of Arizona and the Sonoran Desert, and the saguaro blossom is Arizona's official state flower. In early writings, most often the traditional spelling of saguaro was sahuaro. Since the saguaro must grow in desert lowlands with elevations below 3,500 feet, saguaros can be found in Southern California, Southern Arizona and Northern Mexico.
The saguaro has an amazing internal structure of interconnected woody ribs that grow upright which are covered by a pulpy flesh that gives the saguaro its round appearance. The outer skin is light green in color and is smooth to the touch and the skin is protected by cross pointed spines that help to cool its flesh. The spines also redirect wind and their slightly downward angle helps direct rainwater, which can be absorbed by the saguaro. During a rainfall, the ribs of the saguaro are able to expand in an accordion pleat fashion and a mature saguaro can absorb up to one ton of water. The precious water is stored for seasons of drought. The root system of the saguaro is surprisingly shallow. The main tap root grows to about 3 feet, while the radial roots that strive to attach themselves to rocks to stabilize the cactus, can extend to the approximate height of the saguaro.
Creme colored cactus flowers with yellow centers appear on the ends of the saguaro's arms and the top of the cactus from late April to June, when the cactus is about 35 years old. The flowers are about three inches in diameter, open at night, and remain closed during the heat of the day. Bats, white winged doves and moths drink nectar from the flowers.
The saguaro is fertilized by cross pollination from another cactus. Fruit, about the size of a closed fist, is produced at the end of bulbs and turns a bright red color at maturity. Native peoples such as the Tohono O'odham (formerly Papago) use dried saguaro ribs to gather saguaro fruit for ceremonial wine and candy. Each ripe fruit produces thousands of tiny black seeds. Eventually, the fruit splits open and spews its seeds. This explains why saguaros are found in groups called stands. Some of the seeds are able to pass through the digestive systems of birds and are scattered further from the stand, but only about one in 1,000 seeds survives to germinate. In order for a seed to thrive, it must fall under a "nurse plant or tree" which will provide enough shade for the seed to survive the scorching temperatures. Young saguaros are often found under palo verde, ironwood and mesquite trees.
Extremely slow growing, a saguaro will grow about 1 to 1.5 inches in its first eight years. While a mature saguaro will grow to about 30 feet, some saguaros have been known to reach 60 feet. The average saguaro can weigh between 6 and 10 tons and has an average life span of 150 to 175 years. Arms will begin growing sometime when the cactus is between 50 and 75 years old, and an average saguaro will grow five arms. As a saguaro gets older, its arms begin to droop. Their variety of interesting shapes is a source of fascination and humor.
Mule deer, big horn sheep, pack rats and mice eat the flesh of the saguaro and birds such as the Gila Woodpeckers drill holes called boots into saguaros for nests. Tiny elf owls, bats and a number of other birds and insects make their homes in the saguaro. A saguaro can reseal itself to prevent water loss. The saguaro is a protected cactus and it is illegal to move a saguaro without the proper permit. The Arizona Department of Transportation has been relocating saguaros for the last 20 years, when they have built new roads, and according to an article in The Arizona Republicon May 19, 2011, 71% of the saguaros that were relocated have survived. One of the "secrets" of successful transplanting was not to plant the saguaros too deep. For many years, frost, drought, vandals and thieves and the rapid growth of housing developments all destroyed saguaros, but now an invasion of non native grasses which deplete the water around saguaros and create fuel for wildfires are one of the biggest threats to saguaros
The Saguaro National Monument (East) in Tucson Arizona was created by President Hoover in 1933 as an area to preserve an amazing stand of saguaros that was threatened by cattle and humans even back then. Eventually, The Saguaro National Monument became a National Park. Later, a Saguaro National Park West was developed in the Tucson Mountains. The park and visitors' center is the best place I know of to view and learn about these amazing cacti.
The Sonoran Desert
Cactus Humor by Reg Manning
How to Grow a Saguaro
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