JOSHUA TREE

Drawings and Story

By LLOYD MASON SMITH Director, Palm Springs Desert Museum The fact that the Joshua Tree is not a member of the cactus family usually comes as a distinct surprise to the uninitiated. Its formidable array of long sharp spiny leaves and its irregular method of branching readily suggest close affinity to the cacti. However, if the blossom of the Joshua is examined at close range, it will be seen that this most curious of all desert trees is actually a member of that huge group of plants called the Lily Family. It is rather difficult to visualize a a giant lily over 30 or 40 feet tall and with a "stem" several feet thick; yet, that is exactly what the Joshua Tree is: an overgrown lily.

Not only does this peculiar tree belong to the Lily Family, but it has also been relegated to that division of lilies called the Yuccas. Again, this seems quite an anomaly. However, there are several kinds of Yuccas, and the Joshua is but a rather extreme type.

Botanists refer to the Joshua as Yucca brevifolia Engelmann. Scientific names often tell us a great deal about the plant itself, so let's examine this name more closely. First, the generic name Yucca is merely derived from the Spanish noun "la yuca," spelled with one "c," which is the native name for the relatives of our yuccas that grow in Mexico and such islands in the Caribbean as Haiti. It is generally pronounced "yuh-ka" in preference to "you-ka." The second or specific name brevifolia is taken from two Latin words which mean "short-leaved," in reference to the spine-like leaves of the tree. The proper name Engelmann following the scientific words signifies that he is the botanist who first described and named this particular plant. Engelmann published his original description in 1871, basing his work on specimens procured for him by Clarence King three years earlier from Date Creek, Arizona.

Thus, Date Creek becomes what is termed the "type locality" of the Joshua Tree. Unfortunately, collector King's labels on his specimens failed to specify exactly where on this creek they were taken, and since Date Creek flows through Arizona counties, Yavapai and Yuma, it is undecided as to which county is due the distinction. One of the world authorities on yuccas, Miss Susan McKelvey, thinks the locality should be in Yuma County.

A distinct dwarf variety with leaves but 4 or 5 inches in length may be found in the eastern Mojave Desert of California through southern Nevada to the Virgin River valley in Arizona and adjacent Utah. This different form of Joshua Tree, which may in time be accorded full specific status, was described by Miss McKelvey in 1938. She named it Yucca brevifolia var. Jaegeriana in honor of Mr. Edmund C. Jaeger of Riverside College, noted desert author, who first called this local variety to the attention of botanists. The type locality of Jaegeriana is in the Shadow Mountains of California, near the Nevada state line.

The distribution of the Joshua Tree, oddly enough, spreading across four states as it does (Arizona, Utah, Nevada, and California), coincides almost exactly with the limits of that great geographical area called the Mojave Desert. In fact, so closely can this be depended upon that Dr. Herbert L. Mason, University of California botanist, has stated that the Joshua is a typical plant indicator for the Mojave. This means that wherever you chance upon a Joshua Tree growing in the wild, you can be quite sure you're on that desert.* Do not get the impression, however, that this strangest of desert lilies grows all over this vast region, for that is not the case. Rather, it occurs in scattered clumps, at altitudes usually between 2,000 and 5.000 feet, most commonly at the periphery of the great Mojave Desert; over large expansions it is entirely lacking. In a few isolated and local places this tree may grow in dense colonies, forming veritable forests of Joshuas; in others, only a few trees may be seen in a distance of miles. This sporadic distribution may indicate that at one time the Joshua may have grown across the entire region, or entirely around it if it was once a shallow lake, and that later, changing climatic or soil conditions have eliminated or at least decimated the tree over most of its range, so that it now survives in but a few widely scattered relict patches.

In southern California, just south of Twenty-nine Palms and just northeast of Palm Springs, the late President Roosevelt in 1936 set aside some 838,258 acres of Joshua-treed land as a National Monument. Recent agitation by local miners and homesteaders within the reservation may make it necessary to review the present boundaries, to delete some acreage and to add other areas. At any rate, the public A DECISION OF THE UNITED STATES GEOGRAPHIC BOARD IN 1934 STATES THAT THE NAME OF THE DESERT, OF THE RIVER, AND THE CITY IN CALIFORNIA SHALL BE SPELLED WITH A "J" OF MOJAVE, WHEREAS THE NAME OF THE COUNTY AND THE INDIAN TRIBE IN ARIZONA RETAIN THE "H" SPELLING: MOHAVE. THE WORD IS OF INDIAN, NOT SPANISH, ORIGIN AND MEANS "THREE MOUNTAINS", IN ALLUSION TO THE NEEDLES ON THE COLORADO RIVER, WHERE THE MOHAVE INDIANS ORIGINALLY DWELLED.

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STRANGE LILY OF THE DESERT

has recognized the need to protect at least one natural stand of these yuccas, to preserve them for posterity, and Joshua Tree National Monument is the result.

The Joshua Tree has several other common or vernacular names. Among these are Tree Yucca, Josh Tree, Joshua Yucca, Yucca Palm, Cabbage Tree, Palma, and Yucca Cactus. Naturally such names as “palm,” “cabbage,” and “cactus” are wrongly applied to this lily.

Much speculation has arisen as to the source of the accepted name Joshua. Why should the Biblical name be applied to this tree? Undoubtedly the appellation stems from some early band of Mormons trekking across the Mojave and fancying some resemblance of the Joshuas’ bizarre branching to the great General Joshua who made the sun and the moon stand still. One version says the tree’s spiny arms pointed out the correct route for the travelers; this seems hardly logical, since the branches point in all directions, not one. Another version says they were likened to lifted arms in supplication. The editor of DESERT MAGAZINE traces the origin to a Mormon group led by Elisha Hunt in 1851. However coined, it is the preferred common name for the tree today.

According to Charles Francis Saunders, the first mention we have of the Joshua Tree is in 1772, in the diary of Capt. Pedro Fages who called them “date palms”! The famous Capt. John C. Fremont encountered them in 1844, calling them “yucca trees,” and writing further that they were “the most repulsive tree in the vegetable kingdom”!

In size the Joshua is easily the tallest yucca in the world. Most of the older trees are 20 to 30 feet tall, and individuals over 50 feet in height are not uncommon. The tallest tree yucca ever known formerly grew near Lancaster, California. It was nearly 80 feet tall and 9 feet in circumference! Unfortunately, picnickers maliciously burned it down several years ago!

Yuccas have no growth-rings like hardwood trees, so that you cannot tell the age of any one tree by cutting it down and count-ing its concentric rings. However, it is possible to estimate the age by comparing the size of the tree with the average rate of annual growth. This yearly growth, even under exceptionally optimum conditions, will not exceed an inch annually. Consequently, a tree 60 feet tall, for instance, would be over 700 years old on this basis, and probably about 800. At any rate, these trees should be considered to be hundreds of years old, not thousands.

ing its concentric rings. However, it is possible to estimate the age by comparing the size of the tree with the average rate of annual growth. This yearly growth, even under exceptionally optimum conditions, will not exceed an inch annually. Consequently, a tree 60 feet tall, for instance, would be over 700 years old on this basis, and probably about 800. At any rate, these trees should be considered to be hundreds of years old, not thousands.

Usually the Joshua has but a single stem, which attains a height of from 8 to 10 feet before branching. One rare specimen in California is known to have a straight trunk over 22 feet before branches occur!

There are two main causes for branching in the Joshua. Whenever a terminal branch bears a bunch of flowers, two shoots are produced the next season. And whenever a small weevil, called the Yucca-borer Beetle, eats its way into the tip of a stem and makes a nest of frass there, this injury will also cause the stem to divide. Usually the inner branches of the crown are more or less erect; those on the outer edge are drooping and irregular, giving the tree its unusual outline. Occasionally, new plants may sprout up from the spreading roots, so that you rarely find a whole row of young trees arising from the same root structure. The larvae of a butterfly often attack these roots and may actually kill young plants. The trunk of the Joshua is devoid of the dead reflexed spines, its thick gray or reddish-brown bark broken by narrow deep fissures into well-defined plates. On a dead trunk, this back can be peeled off in big sections. It is very light in weight and spongy in appearance, almost like cork.

Tree yucca roots are long and the size of a pencil, numbering several hundred, extending from the swollen base of the trunk outward and down in true lily fashion. No deep tap-roots are necessary, since the Joshua depends upon the shallow penetrating rain water from desert showers rather than the deeper sub-surface water.

The leaves are narrow and tapering, like stout spines. They are between 10 and 20 inches in length, and minutely toothed along their edges. Instead of dropping off as they die, these leaves bend back against the branches and dry in position, forming a shaggy thick thatch of reflexed and spreading spines. In spite of this apparently invincible armament, many desert animals run up and down the trunks and limbs without any hesitation or hindrance, and some even feed upon these stiff leaves!

Wood rats will trim the trunks to the very top, incorporating the snipped spines into their elaborate nest-piles at the base of the tree. Antelope ground-squirrels (the so-called desert chipmunk) scamper over them in order to devour the flower clusters or to gnaw off the resulting seed-pods.

Thousands of years ago there was a prehistoric monster that lived almost exclusively upon Joshua leaves! This creature was a giant ground-sloth, distantly related to the sluggish sloths now surviving in South and Central America, and was called Nothrotherium shastense. It was too large and bulky to live in trees, and instead crawled leisurely about on the ground, feeding upon the vegetation of the land. That the preferred food of this ground-sloth was mainly yucca leaves was ascertained in 1933 when Gypsum Cave, about 18 miles east of Las Vegas, Nevada, was carefully investigated. This large cave, in which were found the remains and artifacts of a very primitive type of man, was discovered to be floored to a considerable depth with accumulations of sloth dung. Evidently these beasts had used the cave as a shelter, either concurrently or at other times than the native people. Quantities of this dung was analyzed in the laboratory and found to consist nearly 90 per cent of Joshua tree leaf remains! Strangely enough, today the tree yucca does not grow within 20 or 30 miles of Gypsum Cave, one more bit of evidence that this unique tree was more widely distributed at one time than at present.

Hungry cattle have been observed nibbling the new green shoots from low-hanging limbs. Investigation proves that the center leaves can be pulled out without much effort. When chewed, they taste not unlike raw potatoes, and are in fact quite palatable. Jack rabbits evidently relish them as well, for where the branches have been cut off or have fallen to the ground, the leaves are gnawed off by these voracious rodents.

Many birds choose the tops of Joshuas as nesting sites, somehow confident that the down-pointing spines will deter the majority of enemies. Among these should be listed the Desert Sparrow Hawk, the Scott Oriole, the Cactus Wren, the Arkansas Kingbird, and the Red-shafted Flicker. Besides the Desert Wood Rat, already referred to, several species of mice construct their little nests under dead yucca trunks or in bark crevices. Many other animals seek out the Joshua as a source of food. Ground squirrels and kangaroo rats eagerly devour the seeds from fallen pods. The little night lizard and the desert scaly lizard both feed upon larvae, ants, and termites which they find behind the loose bark or under prostrate trees. Of all these creatures which utilize the Joshua in one way or another, none is as dependent upon it as the Night Lizard (Xantusia vigilis). This little reptile, only 2 or 3 inches long and dark gray or nearly black in color, is practically restricted to areas where Joshuas grow, and may only very rarely be found outside of their range. It can be seen by overturning dead trunks, since it shuns sunlight, spending its lifetime in shadow and darkness. If you do seek him out, watch him and then leave him unmolested; he is harmless and only desires to be left alone.

Man has long used the wood of the Joshua Tree economically. Near Soledad Pass in California, this wood was formerly gathered and converted into paper-pulp, and several issues of the London DAILY TELEGRAPH were printed upon yucca paper in 1883! It also has been in demand for use in making surgeon's splints and artificial limbs, and as wood for fashioning novelties, such as book covers, picture frames, pincushions, postcards, screens, and boxes. More recently the pulp has been ground into a fine dust, which when added to beer will make it foam more readily and when mixed withlemon-meringue pie-fillings will make them more fluffy. This com-mercial use is detrimental to the Joshua, for the entire tree is sawed down to obtain the wood, and vast areas of one-beautiful yucca forest near Hesperia, California, are now strewn with rotting Joshua stumps and scattered crowns; only the trunks themselves are carted away by truckloads.

Even the local Indians of the Mojave Desert found many uses for the tree. The fibre they used in weaving sandals and in making tough cordage and rope. The seeds were gathered, pounded into a flour, and made into dough, which was then cooked into edible cakes. Fresh buds and blossoms were either roasted over coals or boiled in water like cabbage. The roots were employed either in coarse wicker-work or in the construction of loosely woven wrapping veneers, or occasionally after pounding in making a fish poison. The dead trunks were used in constructing walls and palisades.

Since we have repeatedly referred to the blossom of the Joshua as being typical of all yuccas, let's look at one more closely. The flowers appear in late February through March to early April, and occur in what botanists term a "panicle," a large cluster of many individual blooms grouped deeply about a common stalk. These panicles occur at the very ends of the branches, and when a tree is in full bloom, present a spectacular sight. Each panicle varies in length from 12 to 20 inches and is about 15 inches wide.

The individual blossom of the panicle is quite large, well over an inch across, fleshy and brittle in structure and greenish yellow in color. There are six petals to each flower. The odor is far from at-tractive, and has been likened to that of the common mushroom. If a flower cluster is brought into a room, the entire place will be soon permeated with the heavy dense musty malodorous stench.

There are six stamens grouped about the ovary. These produce the pollen which is gathered so industriously by the yucca moth. The ovary itself is three-lobed, each lobe in turn divided into equal halves, so that when the seed-pod is eventually formed, it consists of six longitudinal sections. When the pod is ripe, each of these sec-tions is filled with dozens of flat thin nearly round seeds. Each pod, about 3 inches in length, will number several hundred such seeds, and each panicle will bear some 25 or 30 seed-pods. A single Joshua Tree may have as many as 15 or 20 panicles on its terminal stems, thus giving an idea of the great number of seeds produced annually under favorable conditions.

However, the tree yucca does not bloom every year. It may skip a year or years without apparent reason. Whether this is dependent upon the rainfall or temperature is not known; it may be a combi-nation of the two.

Nor does every seed, even if it survives the hungry rodents and birds, reach maturity. About one-fourth the contents of each pod never ripens; the seeds are consumed by the larvae of the yucca moth as if in payment for the fertilization of the blossom. It is indeed a strange partnership that exists between the yuccas and this little white moth. Without the other, neither could exist. This is how it works, as was originally discovered by C. V. Riley back in 1892: Prunuba synthetica is the scientific name for the yucca moth that pollinates the Joshua. When these trees are in bloom, the moths suddenly appear. They are most active in the evening and at night, flying from blossom to blossom until dawn. Let's watch an individual moth. She flies into one opened bloom and deliberately begins col-lecting a small ball of pollen from its stamens. This she does with her fore-feet. If she can't get a large enough pellet at this blossom, she may fly to another to add to her load. Finally, satisfied that she has enough, she carries the pollen-ball to another yucca flower nearby. Here she alights and first backs down between the stamens so that her abdomen is near the ovary of the blossom. Now she carefully inserts her ovipositor into the green tissue and lays a single egg in the ovary. This is her fee for her labors. Next she climbs to the top of the ovary, to the end of the pistil which crowns it, and deliberately crams her little pellet of pollen far down into the stigmatic opening, thus ensuring fertilization. That accomplished, she sets about gather-ing up a fresh load of pollen and repeating the whole process over and over all night long.

When this egg (or there may be more than one if the same flower has been repeatedly fertilized, as has been observed) hatches, the little narva feeds upon the developing seeds in the ovary, which has by this time become a seed-pod. However, each larva only de-vours from 12 to 15 seeds and no more, as if it were actually aware that to eat more would jeopardize its very existence. When it attains its maximum size, the larva gnaws out of the pod and drops to the earth, where it bores its way underground and there pupates, to emerge the next Spring to carry on the unusual cycle! Without the moth, the Joshua could not be pollinated, and without the seed-pods, the young larvae would have no food. Nature is indeed strange in her ways.

Where did the Joshua Tree come from? There is no definite evidence, such as fossils, to answer this interesting question. How-ever, since there are apparently more kinds of yuccas to the south of its present range, it can be assumed that the ancestral tree yucca is from Mexico or further south. In all probability it developed its own pecularities right where it is today, in the region now called the Mojave Desert. No doubt it has been growing here for thousands of years, constantly struggling against the scorching desert winds and the ubiquitous threat of dessication.

In Arizona the Joshua Tree may be seen in three counties: Yuma (around Ehrenberg and Alamo), Yavapai (along Date Creek), and Mohave (near Littlefield and Wikieup). In California it occurs in five counties: Riverside, San Bernardino, Los Angeles, Kern, and Inyo. Four counties in Nevada (Esmeralda, Nye, Clark and Lincoln) and one in Utah (Washington) complete the distribution. Near the Bill Williams River in Arizona the Joshua Tree may be seen growing side by side with that characteristic tree of the southern Arizona deserts, the Saguaro Cactus, which is as typical of the Gila Desert as is the Joshua of the Mojave.

To enjoy your Joshuas to the utmost, you should get out among them. Park your car by the road and walk, or better yet, camp in the center of a yucca forest. Sleep beneath their picturesque and eerily-silhouetted arms. Listen to the desert breezes rasping through their spiny thatches. Watch them become almost animate in the ever-changing moonlight. Seek their meagre shelter during a dust storm, but beware of splitting branches crashing down upon you during such a gale. Sit beneath their shade from the noonday sun and stare out across the desert flat dotted by their grotesque outlines. Poke among the dead trunks and discover what a myriad of desert life you will disclose.

As you do all this, respect their grizzled appearance, their obvious antiquity. Remember that they're relics from the distant past when giant ground-sloths lumbered among them and prehistoric men dwelled in caves nearby. Then will you realize that the Joshua Tree is the most interesting and unusual of all desert plants, one to be protected and cherished as a part of the great unspoiled, unchanged West that is your heritage.

After the bloom at the tip of the heavily pointed branch has faded, these interesting seed pods develop in a huge cluster. From a distance it is difficult to distinguish them from the bloom itself. The Joshua blooms are white, snowy clusters, shining in the bright desert sun. The Joshua cactus usually bloom in the late spring.