Western United States, The

<h2><SPAN name="page_187">THE LIFE OF THE DESERT</SPAN></h2> <p class="indent"> During the blinding glare of summer the deserts of southwestern Arizona and the adjoining portions of California are forbidding in the extreme. Day after day the pitiless sun pours its heat upon the vast stretches of barren mountain and plain, until the rocks are baked brown and it seems as if every particle of life must have left the seared and motionless plants.</p> <p class="indent"> Month after month passes without rain. Now and then light clouds float into sight, and occasionally rain can be seen falling from them, but they are so high that the drops all disappear in the dry and thirsty air long before they can reach the ground. Cloud-bursts may take place about the peaks of some of the higher mountains, but they have very little effect upon the life out on the plains.</p> <p class="indent"> Animals and plants brought to this region from a moister climate must drink continually to make up for the rapid evaporation of moisture from their bodies; a day without water may result in death. And yet the living things that have homes in the desert can resist the dry air for many months without a renewal of their moisture. There are areas where the average rainfall is less than three inches, and sometimes two years may pass without a drop of rain. It will certainly be worth our while to find out something about these desert plants and the way in which Nature enables them to get along with so little water.</p> <p class="indent"> Go where we will, from the moist heat of the tropics or the dry heat of the deserts to the icy north, we find that everywhere the plants and animals are suited to the climate of the particular place in which they live. Therefore we might conclude that they thrive better in those places than they would anywhere else, but that is not always true.</p> <p class="indent"> A struggle is going on continually among plants for a footing in the soil and for a share of the sunshine. The weaker plants are generally killed, while those hardy enough to survive have to adapt themselves to new conditions of life, becoming stunted and deformed upon barren slopes; but they have plenty of room there because fewer plants are striving for the same place.</p> <p class="indent"> It is not likely that the deserts of the southwest have always been as dry as they are now. As the amount of rainfall slowly lessened through thousands of years, the animals could migrate when it became too dry; but the plants, fixed in one place, had either to give up and die, or change their characters and habits to suit the demands of the changing climate. The fact that these extremely dry deserts are filled with plant life to-day is without doubt due to this ability to change.</p> <p class="indent"> In a moist, warm climate plants are luxuriant; they take up a large amount of water through their roots and evaporate it through the leaves. If placed in a desert, such plants would immediately wither and die. To avoid too rapid evaporation the bodies of the desert plants have become smaller, and their leaves have either shrunk greatly or wholly disappeared. Strong-smelling, resinous juices exude from the remaining leaves and stems, and form a surface varnish through which water passes with difficulty.</p> <p class="indent"> Some forms of plant life, such as the prickly-pear, are provided with fleshy stems which hold a supply of moisture to be drawn upon during the long dry season. Men and animals are sometimes saved from death by chewing the pulp of the prickly-pear or other cactuses. After a period of exceptional drought, the stems of the prickly-pear lose their bright green color and become shrunken.</p> <div class="img_ctr" style="width: 413px;"> <ANTIMG src="images/fig081.jpg" width-obs="413" height-obs="293" alt="Fig. 81"> FIG. 81.&mdash;PRICKLY-PEAR, BALL CACTUS, AND SPANISH BAYONET</div> <p class="indent"> The development of the underground part of the plant is frequently out of all proportion to the part above the surface. The manzanita, which grows in the semi-arid climate of southern California, is a low shrub with branches that are rarely large enough for fuel. The roots, however, are large and massive, and are extensively used for firewood.</p> <p class="indent"> The desert plants are armed, not only against the dry air, but against the wandering animals which would bite them and suck their juices. The smell of the sagebrush is such that very few animals will touch it. Other plants are protected by thorns. In fact, the drier the region, the more thorny are its plants. A little shrub called the crucifixion thorn has no leaves at all, nothing but long, sharp spines. Besides the straight thorns there are curved and also barbed ones, for every conceivable form is represented among the plants of these dry lands.</p> <p class="indent"> As the desert plants are armed against the animals, so the animals are armed against each other. Many of the insects and reptiles are extremely poisonous; the greater the heat of their habitat, the more dangerous are their bites. The horned toad, while not poisonous, is protected by having horny spines upon its head and back. The little rattlesnake known as the "side-winder" is perhaps the most dangerous of all, although the tarantula, centipede, and scorpion are formidable foes. The Gila monster, long believed to be so dangerous, is now considered non-poisonous under ordinary conditions.</p> <div class="img_lft" style="width: 282px;"> <ANTIMG src="images/fig082.jpg" width-obs="282" height-obs="383" alt="Fig. 82"> FIG. 82.&mdash;CRUCIFIXION THORN</div> <p class="indent"> The desert tortoise is perhaps the most remarkable of all the animals of the desert. It is rare, and little is known of its habits except that it lives in the most arid valleys of southeastern California, far removed from any water. This tortoise has a diameter across its shell of at least eighteen inches. Its flesh is much prized by the Indians and prospectors. A specimen which had been without water for an indefinite period was dissected, and the discovery was made that upon each side there was a membranous sac, containing clear water, perhaps a pint in all. The desert tortoise, then, carries his store of water with him, and is thus enabled to go many months without a new supply.</p> <div class="img_ctr" style="width: 516px;"> <ANTIMG src="images/fig083.jpg" width-obs="516" height-obs="249" alt="Fig. 83"> FIG. 83.&mdash;THE GILA MONSTER</div> <p class="indent"> A trip across the deserts of the lower Colorado in spring, before the bracing air of winter has entirely gone, is one never to be forgotten. The poisonous insects and reptiles are not at this time warmed up to full activity, while many peculiar plants are just coming into bloom.</p> <p class="indent"> Let us study some of the strange forms growing thickly over the rocky slopes and sandy plains. There are miles of forest, but not such a forest as we are accustomed to see. Tall, fluted columns of the giant cactus (saguaro), with rows of sharp spines, reach upward to a height of from twenty to fifty feet. At one or more nodes, bud-like branches spring from the main trunk and, curving upward, form columns about the parent stem.</p> <div class="img_ctr" style="width: 415px;"> <ANTIMG src="images/fig084.jpg" width-obs="415" height-obs="357" alt="Fig. 84"> FIG. 84.&mdash;THE PALO VERDE TREE AND SAGUARO</div> <p class="indent"> The giant cactus bears near the top a purple flower and a large, edible fruit. This fruit, which has a red pulp, is a favorite food with the Indians, and also with many insects and birds. It is gathered by means of long forked sticks, for if it should drop to the ground it would be broken. The pulp of the stalk yields a little juice or sap which is used by the Indians when hard pressed for water.</p> <div class="img_ctr" style="width: 505px;"> <ANTIMG src="images/fig085.jpg" width-obs="505" height-obs="341" alt="Fig. 85"> FIG. 85.&mdash;A FOREST ON THE PLAINS OF SOUTHERN ARIZONA <p class="imgnote">Showing cholla and saguaro</p> </div> <p class="indent"> Scattered among the huge club-shaped columns of the saguaro is the cholla, the next largest of the cactuses. This species, which is tree-like in its branching and in rare cases grows to a height of twelve feet, bears bright red or yellow flowers. One must approach with care, for its jointed stems are so easily broken that at the slightest touch of the hand or clothing, pieces break off and adhere firmly by means of their sharp curved and barbed spines. Another species of the cholla is small, reaching but a foot or two above the ground, but this and other low forms so cover the ground in places that one has to be constantly on guard to keep from running the spines into his feet.</p> <p class="indent"> These are not all the plants of this wonderful forest. The ocatilla is a cactus-like form having a group of long slender stems bunched together at the root. In the spring each is tipped with a spike of red flowers, and as the snake-like stalks wave in the breeze they present an appearance scarcely less attractive than the saguaro.</p> <div class="img_ctr" style="width: 198px;"> <ANTIMG src="images/fig086.jpg" width-obs="198" height-obs="281" alt="Fig. 86"> FIG. 86.&mdash;OCATILLA</div> <p class="indent"> Scattered among the vegetation just mentioned is the palo verde (green tree), so named from the yellowish green of its bark. It is remarkable for the small size of the leaves, which afford scarcely any shade for the traveller upon a hot summer day. (Fig. 84.)</p> <p class="indent"> Along the dry water courses we find the mesquite, a tree which does not grow upon the gravelly plains and rocky slopes, for it needs more moisture than most of the desert vegetation. In the spring it puts out delicate green leaves which form a pleasing contrast with the other plants.</p> <p class="indent"> Riding through one of these forests in the deepening twilight, one is impressed with a feeling of awe and mystery by the strange, weird shapes outlined against the sky. In the cooler air of evening the animals come from their retreats. The insects and the snakes are then abroad, and if one is on foot the sudden buzz of a rattlesnake is not a pleasant sound to hear.</p> <div class="img_ctr" style="width: 415px;"> <ANTIMG src="images/fig087.jpg" width-obs="415" height-obs="318" alt="Fig. 87"> FIG. 87.&mdash;MESQUITE TREE, SANTA CRUZ VALLEY, SOUTHERN ARIZONA</div> <p class="indent"> The prickly-pear prefers slopes not quite so dry and hot as those of the forest just described. Its broad, spade-like, jointed stems are very interesting. The red fruit clustered upon their extremities is not disagreeable to the taste, but is covered with a soft, prickly down.</p> <p class="indent"> Associated with the prickly-pear is a species of agave, but this does not grow so large in Arizona as it does farther south in Mexico. The plant is familiar to us as the common century plant of our gardens. The long fleshy leaves with spines at the ends are clustered at the surface of the ground, and from their centre, at blooming time, rises a tall flower stalk. The agave requires many years to mature. When the flower stalk has once started it grows rapidly, but after blossoming the plant dies.</p> <p class="indent"> The mezcal, or pulque, the national drink of the Mexicans, is made from the sap of the agave. The fibre of the agave, known as sisal hemp, is used in the manufacture of rope, twine, mats, brushes, etc. Other parts of the plant have various uses.</p> <table style="width: 435px; margin-left: auto; margin-right: auto;"> <tr> <td style="width: 182px; vertical-align: bottom; padding-right: 50px;"> <ANTIMG src="images/fig088.jpg" width-obs="182" height-obs="279" alt="Fig. 88"></td> <td style="width: 203px; vertical-align: bottom;"> <ANTIMG src="images/fig089.jpg" width-obs="203" height-obs="279" alt="Fig. 89"></td> </tr><tr> <td style="text-align: center; vertical-align: top; padding-right: 50px; font-size: smaller;"> FIG. 88.&mdash;THE AGAVE</td> <td style="text-align: center; vertical-align: top; font-size: smaller;"> FIG. 89.&mdash;SPANISH BAYONET IN BLOOM</td> </tr> </table> <p class="indent"> There are many kinds of yucca in the more elevated portions of the desert. They range in size from those only two or three feet high, of which the Spanish bayonet is a type, to the giant yucca of the Mohave Desert, which attains the proportions of a tree and forms thick forests over an area of many miles. The Spanish bayonet, with its long stalk of white, waxy blossoms, presents a very beautiful appearance, as do also the young specimens of the tree yucca.</p> <p class="indent"> At rare intervals, once perhaps in many years, there is an unusual amount of rainfall in the spring, and in a few weeks the desert becomes transformed as if by magic. Seeds germinate, the presence of which one would never have suspected in the drier weather. In an incredibly short time the long gravelly or sandy slopes about the bases of the mountains are covered with a veritable carpet of green, yellow, and red. The sand verbena, the evening primrose, baby blue-eyes, and different kinds of lilies grow so thickly in places that every footstep crushes them.</p> <div class="img_rgt" style="width: 212px;"> <ANTIMG src="images/fig090.jpg" width-obs="212" height-obs="289" alt="Fig. 90"> FIG. 90.&mdash;YOUNG YUCCAS IN BLOOM</div> <p class="indent"> But in a few short days the beauty has disappeared. The seeds mature speedily and drop into the sand. A hot wind withers the stems and leaves and blows them away; drifting sands take the place of the rich carpet. How readily these plants have adapted themselves to the brief period in which life is possible!</p> <p class="indent"> Thus it is that this vast region about the lower Colorado, although so dry and hot, and at first sight apparently so unfitted for sustaining life, nevertheless supports its share. Many of the plant forms have assumed strange and monstrous shapes in their efforts to withstand the hard conditions in the struggle for existence, while others simply lie in waiting, sleeping during the long dry year, but ready to spring into life when the favorable showers come, as they sometimes do.</p> <div style="break-after:column;"></div><br />