Joshua Tree (Yucca Brevifolia)

{Click on an image to enlarge, then use the back button to return to this page} This page last updated on 06/12/2017 (Fig. 01) Picture Notes: The Joshua Tree in (Fig. 01) was taken on 02/24/2011 on a trip to the Wee Thump Joshua Tree Wilderness Area located 8 miles west of Searchlight on route 164, also known as the Joshua Tree Highway. "Wee Thump" is Paiute for "ancient ones."  At first glance, this flat, gently sloped alluvial plain between Searchlight and Nipton appears rather plain and boring; however, it offers a wide variety of plant life and occasionally, for the patient, glimpses of birds, lizards and other desert animals. After spending a couple of hours wandering the area I came upon this Joshua Tree, which without any doubt in my mind is one of the largest I have seen. Then on a subsequent visit in 2016, I captured this picture of my hiking partner Jim Herring standing in front of yet another large Joshua Tree in the Wee Thump Joshua Tree Wilderness Area. The picture in (Fig. 03) was taken near Barstow California, while exploring the site of the June 8th, 1966 crash site of the XB-70 VALKYRIE. (Fig.02)

Description: Joshua Tree (Yucca Brevifolia). Though it is not actually a tree, the Joshua tree is a giant yucca plant--Yucca Brevifolia--the short leaved yucca. The Joshua tree, the largest of the yuccas, grows only in the Mojave Desert. Natural stands of this picturesque, spike-leafed evergreen grow nowhere else in the world. Its height varies from 15-40 feet with a diameter of 1-3 feet. They grow 2 to 3 inches a year, takes 50 to 60 years to mature and they can live more than 150 years. In bloom, the Joshua tree features clusters of creamy white flowers. Its bell-shaped blooms, 1.25 to 1.5 inches large, each with 6 creamy, yellow-green sepals, crowded into 12 to 18 inch, many-branched clusters with an unpleasant odor. The trees bloom mostly in the spring, although not all of them will flower annually. The fruit is elliptical and green-brown. Six-celled, 2.5 to 4 inches, and somewhat fleshy, it dries and falls soon after maturity in late spring revealing many flat seeds.  Like most desert plants, their blooming depends on rainfall at the proper time. They also need a winter freeze before they bloom. Once they bloom, the trees are pollinated by the yucca moth, which spreads pollen while laying her eggs inside the flower. Joshua trees (and most other yuccas) rely on the female pronuba Moth (Tegeticula) for pollination. No other animal visiting the blooms transfers the pollen from one flower to another. In fact, the female yucca moth has evolved special organs to collect and distribute the pollen onto the surface of the flower. She lays her eggs in the flowers' ovaries, and when the larvae hatch, they feed on the yucca seeds. Without the moth's pollination, the Joshua tree could not reproduce, nor could the moth, whose larvae would have no seeds to eat. Although old Joshua trees can sprout new plants from their roots, only the seeds produced in pollinated flowers can scatter far enough to establish a new stand. It is difficult to determine the age of these plants since they don't have "growth rings" like real trees, but many are believed to surpass 700 to 1000 years in age. Yucca brevifolia is endemic to the Southwestern United States with populations in western Arizona, southeastern California, southern Nevada, and southwestern Utah. This range mostly coincides with the geographical reach of the Mojave Desert, where it is considered one of the major indicator species for the desert. It occurs at altitudes between 1,300 and 5,900 feet.  Considered ugly by many, these trees come in a wide variety of shapes. The plant was supposedly named by the Mormons who thought it resembled the biblical Joshua welcoming them with upturned arms. (Fig. 03)