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Published: March 13th 2010
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We are coming to a close of our stay in Tucson. We will hitch up and head out next Tuesday morning for Mesa AZ, where we will be hosted to some fine barbecue that evening by my good friend Dave and his lovely wife Mare. On March 18, we will continue west to Indio, CA where we will spend a few days and visit with Nan’s cousin Dorothy and her husband Tim, who winter in the vicinity of Desert Hot Springs.
Friday, we made a day trip to Sabino Canyon, nestled in the foothills of Arizona's southern Catalina Mountains, 12 miles from downtown Tucson. Said to be one of the most scenic spectacles in Arizona, this paved road runs 3.8 miles into the canyon, crossing 9 stone bridges over Sabino Creek. It begins at an altitude of 2,800 feet and rises to 3,300 feet at its end.
Private vehicles are not allowed on the canyon road, so the only way up is by foot or via a motorized shuttle tram with open air seating into which visitors can jockey for $8.
Winding through the canyon, visitors who follow the road by foot or shuttle have views of the
creek, the riparian vegetation, magnificent Saguaros on the canyon walls, and towering rock formations. Picnic areas are scattered along the road, as are trailheads leading to other sections of the National Forest or paralleling the road.
Archaic nomads used the Sabino Canyon area for thousands of years hunting small game in the canyon. The earliest visitors were probably of the Clovis culture 12,500 years ago, and later, as the climate changed, the Cochise culture became dominant about 8,000 years ago. About 1500 ago, farmers of the of the Hohokam culture occupied the canyon and archeological excavations of their culture continues in the canyon to this day. They disappeared about 1500 and were replaced by the Pima and Tohono O'odham Indians, who still inhabit the Tucson area today. Google “sabino canyon” to read more.
Sabino Creek flows 9 to 12 months of the year, making it unique in the Tucson area. The canyon has good examples of riparian and desert flora. Riparian areas have cottonwoods, willow; walnut, sycamore and ash trees. Foothill plants include Mesquite, Palo Verde, Brittlebush, Saguaro and many other cactus.
You can see from the photos uploaded for this entry that the canyon is punctuated
by the Saguaro ("Sah-wah'-ro”) cactus. Some of the stately twenty to fifty foot Saguaro have been around since Teddy Roosevelt became President in 1901. A few still living today were tiny young upstarts, perhaps growing under the shelter of a Paloverde tree, when Thomas Jefferson was elected President in 1801.
If you want to know whether a Saguaro is full or thirsty, you can tell by its vertical pleats. Talk about water retention! The outer pulp can expand like an accordion, plumping without splitting, so the fleshy tissue can absorb a great quantity of water, sometimes increasing its weight up to 2,000 pounds. This turgid cactus would collapse without its interior framework of woody, tissue-like, bamboo fishing rods arranged parallel to form a cylinder shape. This lightweight framework of ribs around the thick, whitish pith is surrounded by fleshy tissue.
When the pleats are more deeply shadowed, more defined, drought has shaped the cactus. The plant can lose up to 82 percent of its moisture before it dies of dehydration. In times of little rain, shallow roots near the soil's surface can capture the moisture of even the lightest rainfall. The roots spread out in length as long
as the cactus is tall.
The downward-pointing spines, "drip tips," also help by directing rainwater toward the base of the plant. These clusters of spines also play a role in cooling the outer skin; they help deflect wind and provide insulation from freezing as well.
Conserving water loss is essential to the survival of the Saguaro. When the sun beats unmercifully on its waxy, watertight, outer surfaces, microscopic pores close. At night, when temperatures are lower, the pores open, allowing entry of carbon dioxide, necessary for photosynthesis and the manufacture of carbohydrates.
The Saguaro can grow only in narrow environmental niches within the Sonoran Desert, usually below elevations of 3,500 feet. Freezing temperatures and frosts can kill or damage the delicate plant. Wild arms and drooping limbs may indicate that a particular plant survived a bitter winter.
These distinctive human-like arms begin to grow only in middle age, about 75 years, after achieving a height of 14 to 16 feet. The oldest, with dozens or more branches, have marked the passage of many years.
Another feature of the Saguaro, the many holes on its body makes one wonder if the Gila Woodpeckers inflict much damage
as they hammer into the tissues used to store water. Often, these meticulous birds drill 2 or 3 holes before they are satisfied. But the plant quickly minimizes damage by sealing off the wound with callous scar tissue to stop water loss.
Another guest of the Saguaro, the Gilded Flicker, is not always so benign. Flicker nests have been found in about 20 percent of all dead Saguaro. Sometimes while pecking, they can break the internal framework at the joint of an arm , leaving it vulnerable in windstorms to loss of the limb.
After the woodpeckers leave, welcoming hollows remain, where other birds nest and raise their young. Inside, where it is cooler by day and warmer at night, one might see the yellow eyes of a small Screech Owl; a pair may occupy the same nesting place for 7 or more years.
Shiny-winged Purple Martins and colorful House Finches will also call the Saguaro home for a time. Sometimes the non-native Starling will dispossess native birds of their Saguaro nests leaving them out in the heat and cold. Red-tailed Hawks and Harris Hawks will nest aloft, from where they can see their scurrying prey sharing
in the spring beneficence of the Saguaro.
Saguaros first blossom when they are 50 to 60 years old (7 to 8 feet tall), and do so for only one night. Crown-like clusters of creamy white flowers bloom near the ends of branches in May and June. These short-lived flowers, with an aroma similar to overripe melon, open fully by midnight.
Suddenly, Long-nosed Bats will swoop out of the night sky to probe the just-opened blossoms for nectar with their long tongues. Pollen accumulated on their faces and fuzzy fur will be scattered to hundreds of other flowers before daylight.
The following morning, bees and wasps will buzz deep into the funnel-shaped blooms, brushing against anthers, the pollen bearing part of the stamens, then flit to another flower. Harvester ants and butterflies will arrive and drink their fill as well. If you hear a bird atop a branch calling in a distinctive voice, "Who cooks for you," it is probably that primary propagator of the Saguaro, the White-winged Dove.
By midday, the 24 hour flower closes forever. If pollination has occurred, a small fruit will begin to grow at the base of the flower. As temperatures rise
in the desert, another sweet gift of the Saguaro will tempt the hungry.
When the fruits ripen, doves will consume large quantities of seeds. Looking for a tasty morsel, the Kangaroo Rat might soon arrive along with various squirrels, pack rats and pocket mice. These may shortly be driven away by the larger coyote, foxes and skunks. With so many feeding on the bounty of the Saguaro, it is a wonder it survives at all. But the sheer numbers of seeds produced, sometimes more than 2,000 in an individual fruit, give the Saguaro 40 million-to-1 odds in favor of reproducing.
But more danger lies ahead for the vulnerable Saguaro. Lightning strikes during the desert's wet season can take a large toll on the Saguaro. Bacterial infection may set in, and "Saguaro rot" can cause death within a week.
By the middle of July, waves of heat will shimmer across the Sonoran Desert landscape. The air temperature will climb to 120 degrees Fahrenheit, while the surface temperature soars to 200 degrees. Empty husks of fruit will litter the desert floor where Pack rats scamper, chewing over the remains of this year's banquet. One seed may drop from a
whisker and land in the protective shade of a Paloverde tree.
A tiny new symbol of the West may beat the odds to take root on a stony bajada of the Sonoran Desert... Hopefully, standing tall in the year 2200, it will have its own tales of a New West to tell.
Happy trails!
Paddy
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Terry
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Saguaro
Pat and I enjoyed seeing these unique plants when we visited Tucson in July! The temperatures (116 degrees) did not invite us outdoors for very long. You saw far more than we ever did! See you soon, neighbors!