A Tree Named Joshua

By Sandra L. Keith

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    Many people know the names of trees such as elm, maple, cedar, walnut, pine, or sycamore. But how many of them have heard of a Joshua tree or know that such trees exist?

    It is believed that the Joshua tree was first named by early Mormon pioneers who thought the many outstretched arms or branches of the plant resembled Joshua praying for victory at Jericho. So they called it the Joshua tree or praying plant. However, the Joshua tree is actually a member of the lily family and its scientific name is Yucca brevifolia.

    The Joshua tree is found in only a few isolated areas of the southwestern United States. Its crazy shape dots the high deserts of Nevada, Utah, and Arizona, growing mostly above the 3,000-foot level where the average rainfall is between eight and ten inches a year. But it is within a small section of southern California in a place where the Colorado River and Mojave Desert quietly slip together that the tree reaches its highest stature and greatest beauty. This is truly Joshua tree country. Here, within the higher elevations of the 870 square miles known as Joshua Tree National Monument, the tree flourishes.

    In the warm spring months of March and April plants in every direction begin to liven up. They put forth shiny green leaves and jewel-colored flowers with petals as smooth and fragile as butterfly wings. Yet it is the Joshua tree that dominates the landscape and reigns as king. Reaching as high as forty feet, the tree’s shaggy-armed branches boast a new sight. Huge green and white flowers burst forth and sit like heavy crowns upon the jagged clusters of dark green leaves.

    It is fitting that the Joshua tree be allowed this kingly time for boasting, for it is one of the oldest living things on the desert. Yet the exact age of these large trees remains a secret, for the Joshua tree does not form annual growth rings.

    Surprisingly, the soft, cork-like bark hides a hollow trunk that ranges from two to five feet in diameter at its base. The tree’s rough gray trunk sprouts many long, slim branches or arms. Sometimes a branch is shaped like a pencil with just one group of short leaves upon its tip. Other times a branch will divide into a wishbone-like tip, and each tip holds its own dense cluster of sharp, dagger-shaped leaves.

    While other plants bloom each spring, the Joshua tree does not. The time between flowering is probably determined by temperature and rainfall. But its big, pineapple-shaped flowers are important, because they are one of the reasons for the strange shape of the Joshua tree.

    The Joshua or yucca tree will not form those many arm-like branches unless the leaf-making bud at the end of a branch is killed, which happens when a branch begins to flower. Another reason for the unusual twisted shape of the Joshua tree is the activity of the yucca boring beetle larvae that live and feed on the ends of the branches, where they destroy the leaf-making buds.

    The Joshua tree is useful to man as well as beast. The smallest of the tree’s roots are red and were used by Indians for weaving colorful designs into their baskets. The wood from the yucca is soft and easily shaped. It is used to make a special kind of surgeon’s splint. It is also cut into thin sheets of veneer from which unusual trinkets are made.

    However, it is really the desert birds, mammals, and insects who benefit most from the Joshua tree. The little yucca night lizard relies completely upon this plant and could not survive without it. Living either just under the bark of a growing tree or in the dark hollows of a fallen rotting trunk, this little reptile dines on the insect larvae, ants, and termites it finds there.

    A small animal known as the wood rat or pack rat uses the sharp spines or leaves of the Joshua tree when building its nest. It scampers up a living tree and, with great determination, chews off one of the leaves. Hurrying back to its hideaway, the rat will use that pointed leaf end to form a sort of barbwire fencing to keep invaders away from its underground headquarters.

    At least twenty-five different birds are known to make their nests in the Joshua tree. Two of these, the cactus woodpecker and the red-shafted flicker, make a nest by digging a hole in a branch or the trunk of the Joshua tree. Sooner or later they will leave this home and a new tenant will move in—a western bluebird, a Pasadena screech owl, an ash-throated flycatcher, or some other kind of bird. In any event, the nest will be used for many years.

    The Joshua tree forests continue to thrive. New plants still sprout as the seeds are carried off and dropped by some little desert rodent; or perhaps they are blown away upon the hot, dry winds. The larger trees produce not only seeds but peculiar underground runner-stems that eventually push upward and break through the sunbaked ground, and a new Joshua tree begins to grow.

    Illustrated by Shauna Mooney