The Saguaro Cactus, also known as Carnegiea gigantea, is a rugged plant built to last in especially rocky terrain. Not to mentions, an extreme tolerance to sweltering heat and dryness.

The magnificent Saguaro Cactus, the state flower of Arizona, covers many of the desert slopes, flats, and rocky bajadas or lowlands of the Sonoran Desert of southeastern California, southern Arizona, and northeastern Mexico. But, the best place to find one of these cacti is the preserve west and south of Tucson, Arizona.

Saguaros have a smooth and waxy skin which surrounds its tall, columnar stem in a vertically ribbed fashion. This in return allows the cactus to absorb large amounts of water, that is, when water is available. As the cacti absorb this water, the outer pulp expands like an accordion. The stem of the cactus can reach a diameter of 18-24 inches. Consequently, as the diameter of the stem grows, so does the plant's weight, possibly increasing by up to a ton.

Covering the skin of the cactus is many spines about 2 inches in length. The downward pointing needles help direct wind, insulate the outer skin, and make it easier to direct rainwater into the depression of the cactus.

While the Saguaro can absorb a large volume of water, it does not necessarily need to. It may survive with little or no rainfall. The plant relies on the stored moisture of the ribs and other parts that make up the strong framework including: a woody tissue, thick whitish pith, and a fleshy tissue. And to hold this framework in place, the Saguaro Cactus is equipped with an amazing root system. Its tap root is only about three feet long, which is really shallow for such a plant. From this tap root it has two sets of radial roots, consisting of, a thinner root system which grows to a length equivalent to the height of the cactus, and a much thicker root system that only grows to approximately a foot long. Together these systems work to obtain water and provide for the Cactus.

Despite rainfall, the Saguaro cactus grows very slowly, often beginning life in the shelter of a "nurse" tree or shrub. This provides a shaded, moist habitat for germination. Once growing, the cactus can grow to a great height, 15 to 50 feet. But this only occurs over many, many years, as the Saguaro Cactus may only grow an inch per year. Its slow growth and great capacity to store water allows it to flower each year. The night-blooming flowers bearing creamy-white petals around a 4 inch tube, encircle a dense group of yellow stamen which occupies the top of the tube. Sweet nectar gathers in the bottom of this tube, attracting many birds and insects. The Saguaro can only be fertilized through cross pollination. Once fertilization occurs, a 3 inch, oval shaped, green fruit ripens and eventually splits into a red, pulpy flesh, which animals and humans can enjoy together.

These are beautiful plants for the landscape of desert environments. Since they grow slowly, they can be held in a garden, or even a pot, for many years. However, do not expect them to grow fast, for many of the larger specimens are hundreds of years old.

My Cactus Links.....

http://www.desertusa.com/july96/du_saguaro.html

http://www.blueplanetbiomes.org/saguaro_cactus.htm

http://everything2.org/index.pl?node=Giant%20Saguaro