Cactus Forest Drive, Saguaro National Monument

by Anonymous

CONSERVATION—CAN A LAYMAN HELP?

If you are interested in the work of the National Park Service and in the cause of conservation in general, you can give active expression of this interest, and lend support by aligning yourself with one of the numerous conservation organizations which act as spokesmen for those who wish our scenic heritage to be kept unimpaired for the enjoyment of future generations.

Names and addresses of conservation organizations may be obtained from the ranger.

KEEP AMERICA BEAUTIFUL

Ray Manley photo

THE NATIONAL MONUMENT

In 1933 President Herbert Hoover by presidential proclamation created Saguaro National Monument. Within its boundaries is found the magnificent forest of mature Saguaros that is recognized as the finest stand of this great cactus in the United States. It is one of the few National Monuments dedicated to the protection and preservation of a native plant species.

It is also one of the most diversified of our National Monuments. With an altitudinal range of over 5,000 feet its 63,000-acre area encompasses the peaks of two mountain ranges. Against this background of towering mountains the cactus forest is presented as a rare jewel mounted in an incomparable setting.

THE GIANT CACTUS

The Saguaro (Carnegiea gigantea) is the largest cactus native to the United States. Common in northwestern Mexico, its range north of the border is limited to southern Arizona, with the exception of a few isolated small colonies along the California side of the Colorado river. It grows on low desert plains and foothills in the hot dry climate of the Lower Sonoran Zone. A prominent feature of this desert landscape is the great variety of xerophytic (especially modified to exist on limited water supply) plants, especially the cacti. In response to the arid conditions under which it must survive the Saguaro exhibits a degree of adaptability equalled by few plants anywhere.

The construction of the Saguaro is simple, yet effective. The stem is supported by an inner framework of from 12 to 30 slender vertical ribs. Arranged in a circle and joined at various places these ribs form an openwork tube that possesses great strength and rigidity. In and around this tube is a spongy tissue capable of absorbing a great amount of water. This is facilitated by the accordion-like pleats of the interior surface of the stem. These extend or close together as the moisture content of the plant increases or diminishes.

The roots that serve this living storage tank are no less remarkable. The tap root is small and acts as little more than a pad to support the great weight of the plant. The radial roots are heavy and of great length. They radiate out from the base of the Saguaro, usually no more than a foot below the surface of the ground, but often to a distance equal to the height of the plant. They serve the double purpose of gathering food and moisture, and of holding the great bulk of the trunk upright against the fierce desert storms. In their progress through the rocky soil in which the Saguaro usually grows they become contorted and act as anchors which are not easily dislodged.

George Olin Photo
The red pulp and shiny black seeds of the Saguaro fruit are eagerly taken by almost all animals. Even man finds it delicious. The scarlet lining of the opened and split pod is often mistaken by newcomers for a red flower.

Ray Manley Photo
The Saguaro blooms at night, and on bright days closes about 10 the next morning. They attract swarms of insects, which in turn lure many birds. This is the state flower of Arizona and blooms in May and June.

The associations of the Saguaro with other plants of the desert have not as yet been fully studied. However, it is apparent that for the first years of its life the young Saguaro seedling requires the protection furnished by a shrub or tree. Here it makes slow but steady progress until at 50 years of age it may be 10 to 12 feet tall. During the next century it may attain a height of 40 feet and a weight of several tons, dwarfing its protector of former years.

The ecological importance of the Saguaro to animals is better known. Two species of Woodpeckers, the Gila Woodpecker and the Gilded Flicker, drill deep holes into the plant and fashion nests in the cool interior. Actually this causes little damage to the Saguaro, which soon forms a thick scar tissue around the walls of the excavation, sealing it away from the rest of the plant. In succeeding years these nests may be taken over by Elf Owls, Sparrow Hawks, Flycatchers, or Purple Martins. Larger birds build their nests among the branches of the Saguaro. Chief among these are the Red Tail Hawks and Great Horned Owls.

Ray Manley Photo
YUCCA BLOOMS

Yucca elata (Palmilla, Soapweed) is one of the best known plants of the Southwest. The beautiful white plumes of flowers appear in May and June.

CACTUS FOREST DRIVE

While at Saguaro you will find it is desirable to take advantage of the recreational and educational facilities provided for your use. After you leave the Administration Building, signs along the 9.1-mile loop road will direct your attention to special exhibits along the way. Each area has been chosen because of features especially interesting to the visitor. Limited exploring and hiking trips are encouraged along Cactus Forest Drive. A picnic area provided with fireplaces, tables and ramadas is located at the 8-mile point.

Among the many stops along the Cactus Forest Drive five have been selected as especially important to an understanding of the natural features of the Monument. Each has “in place” information which will add to your appreciation of the Cactus Forest.