Sunday, February 5, 2012

Saguaro National Park

I am still catching up with the Arizona photos. I think, however, that this is my last posting with Arizona pictures.

On one of the last mornings before leaving the Tucson area, we decided to visit Saguaro National Park, which is located just down the road from Tucson Mountain Park where we were camping. This park is divided into two sections located 30 miles apart: one is west of Tucson and the other east. We were at the west portion of the park. Together they preserve over 91,000 acres of the Sonoran Desert and a million and a half Saguaro cacti, which have been protected in the park since 1933.

Here is a shot of the main visitors' center.

Most of the park is designated as wilderness.

There is a five mile loop drive.  Due to the roughness of the road, we drove only the west mile to gain access to the Signal Hill Picnic Area.  There is a short half mile walk that takes you up to an area that has prehistoric rock art.

Old cactus blooms.....

I must admit that I love the desert, but this is not a good place to bushwhack.  If you do, you are bound to end up with cactus spines.

For centuries  peoples of the Sonoran Desert have used products of the saguaro.  In summer the cacti produce a nourishing bounty of juicy fig-like fruits.  Tohono O'odham Indians knock them off with long poles.  They use the fruit to make jam, syrup, and for religious ceremonies -- wine. 

Many features help the saguaro store and conserve water.  Accordion-like pleats allow the cactus to expand and hold water collected through its roots.  Spongy flesh in its trunk and branches serve as a reservoir for water, storing it as a slow-to-evaporate gelatin substance.  Unlike most plants, the saguaro has no conventional leaves.  Photosynthesis is instead carried out by the trunk and branches.  Spines shade the plant, shield it from drying winds, and discourage animals.  Waxy skin also aids in reducing moisture loss.

Saguaro collect water with a network of roots that lies about three inches below the desert surface and stretches as far from the main trunk as saguaros are tall.  In a single rainfall, these shallow roots may soak up as much as 200 gallons of water -- enough to last a saguaro for a year.

The Sonoran Desert, which stretches across the American southwest and into Mexico, supports 25 species of cacti.  A saguaro begins life as a shiny black seed no bigger than a pinhead.  One saguaro cactus produces tens of thousands of seeds a year and as many as 40 million in its lifetime of between 175 and 200 years.  Most of the seeds that survive grow under nurse trees like palo verde and mesquite.  These cacti grow very slowly, especially at first.  By the end of a first year after sprouting, the young seedling is only 1/4 inch tall.  After 15 years, it may be barely 12 inches tall.  At 30 years saguaros begin to flower and produce fruit.  By 50 years the saguaro can be up to seven feet tall.  After 75 years it may sprout its first branches, or arms.  By 100 saguaro may reach 25 feet.  A full grown saguaro may tower 50 feet and weigh in at 16,000 pounds!  They die from old age, animals, lightning, cactus poaching, vandalism, freezing temperatures, wind, and drought.

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