[Illustration: 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.
[Illustration: 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._]
[Illustration: 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.
[Illustration: 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.