It may seem a bit odd having a picture of a Joshua Tree on the main page of a Heart Institute website, but the Joshua tree and the Heart Institute of the High Desert are inextricably linked. In the US, there are two deserts, the Mojave (also called the "high desert") and the Sonoran (rarely called the "low desert"). The Joshua tree is characteristic of the high desert, as opposed to the low desert in which the barrel cactus is more common.
The Joshua tree's classification is as follows:
It is a member of the Yucca genus, thus its name: Yucca brevifolia -- Yucca with short (brevi) leaves (folia). The related Yucca glauca has leaves as long as 91 cm, whereas brevifolia has leaves 36 cm long. The name Joshua Tree has been attributed to Mormon immigrants, who while migrating west, noted that the trees branches looked like the arms of the prophet Joshua outstretched in prayer.
Joshua trees are found only in the Western US in the Mojave Desert region between 2,000 and 6,000 feet in altitute (high desert). They extend throughout Southeastern California, Arizona, Nevada and even Southern Utah. There are two types of Yucca brevifolia. Var. jaegerians grows in the Eastern Mojave and var. herbertii in the Western Mojave.
The "tree" is composed of many fibers, but no annual growths rings, so its age is difficult to determine. Typically, they grow about 1/2 inch per year, thus you can estimate its age by its height. The root system is very shallow, and with much of the weight of branches fairly high, it can be unstable. The Joshua tree was used extensively by native Americans because of it's fibrous structure. The leaves could be woven into a variety of containers and even clothes. The seeds were also part of the diet. Early settlers also used the tree for fuel and fencing.
The Joshua tree blooms every spring, giving beautiful off-white flowers at the tips of its branches. These flowers given edible seeds.