Saguaro Cactus - Part of Sonoran Desert on the North American Continent - Essay Example

The saguaro has many unique characteristics that make it a perfect icon for survival in the harsh landscape of the Arizona desert.
Getting as large as two feet in diameter and 30 feet tall, it is perhaps surprising to a media-educated audience to discover that the saguaro only grows on desert slopes and flats in primarily Arizona and that it actually seems to prefer a rocky environment. According to DesertUSA (“Saguaro Cactus”, 1996), the cactus “is supported by a tap root that is only a pad about 3 feet long, as well as numerous stout roots no deeper than a foot, emanating radially from its base.

Smaller roots run radially to a distance equal to the height of the saguaro. These roots wrap about rocks providing adequate anchorage from winds across the rocky bajadas.” These shallow roots enable the cactus to absorb scant rainwater from a larger area before it has had a chance to evaporate or sink beyond reach – “a mature plant may soak up as much as 200 gallons of water during a storm” (Epple, 1995). The fluted nature of the columns is also developed to help collect more water as these sections expand to allow the plant to absorb water during the wet season and shrink like an accordion to reduce moisture loss and provide some cooling in dry times.

The cactus also grows very slowly, living for as long as 200 years. This, coupled with the supporting structure of the plant itself provides biologists with a chance to study climate change. This also allows the plant to flower each year. The flowers are about three inches wide and have creamy white petals that surround a yellow interior with a deep tube entering into the plant. They only open at night, a few at a time from May through June, so as to lose as little water as possible, but they can stay open until noon the following day waiting to be pollinated from another plant. If they are pollinated, the fruit begins to form immediately, but if they are not, that particular flower will not reopen again. This again is a development intended to conserve resources. This is essential not only for the cactus but for the other living things in the desert as well.

The cactus depends on other living things in the desert to help it with the regeneration of the species and in return, it provides a lot of materials required if life is to flourish. Beginning the cycle with the flowers, the tube of the flower develops very sweet nectar at its base, enticing animals such as birds, bats, and insects which pick up and drop off the pollen as they feed. The pollinated flower then begins the process of creating the fruit. The fruit is about the size of a kiwi and green in color. It ripens just before the rainy season starts, roughly around October, and falls to the rocky ground. The fruit splits open on the hard ground below to reveal the pulpy, bright-red flesh inside. Within each fruit are as many as 4,000 seeds that are eaten with the flesh by the many animals that will feed off of it, later to be deposited with the feces in relatively protected areas.

Animals that eat from the saguaro include pack rats, jackrabbits, mule deer, coyote, cactus wrens and bighorn sheep (National Park Service, 2003). These animals will sometimes use the plant as a source of water during dry seasons as well. As the plant grows and becomes more tree-like, it also provides a home for desert animals. The gilded flicker and the Gila woodpecker typically start this process by hollowing out cavities within the ‘trunk’ of the plant. These “birds excavate new holes each spring and reject several cavities in one nesting season before settling in one and raising a family. Their industriousness leaves many holes for other animals, who rapidly move-in” (Uhler, 1995).

The discarded holes and holes left over from the past then become holes to all new animals including the American kestrel, cactus wrens, Lucy’s warblers, elf owls, purple martins, screech owls and western kingbirds. “Honeybees also inhabit some of the discarded holes of the saguaro cactus. For residents, the holes are a retreat from desert temperature extremes. Well insulated by thick walls, the holes are as much as 20 degrees cooler in summer and 20 degrees warmer in the winter. Other saguaro dwellers live in bulky nests. These include the red-tailed hawk and Harris hawk” (Uhler, 1995). In addition to the animals, the cactus also provides needed material for human desert dwellers. Read More