Joshua Tree

Yucca Brevifolia

Joshua tree (Yucca brevifolia) is a large, branching yucca native to the Mojave Desert. It is a succulent rather than a true tree and commonly reaches 15 to 30 feet in height, with rare individuals near 40 feet. Many live for several hundred years.

Two subspecies are generally recognized. Yucca brevifolia subsp. brevifolia is taller and occurs mainly in the western Mojave of California. Yucca brevifolia subsp. jaegeriana is shorter, more compact, and occupies the eastern Mojave in Nevada and Arizona. Each form is pollinated by a different yucca moth: Tegeticula synthetica in the west and Tegeticula antithetica in the east. Successful reproduction depends on this relationship.

Growth is slow, usually only a few inches per year. Flowering requires favorable conditions including winter cold and adequate moisture. Rodents disperse many of the seeds by caching them in the soil.

The species occupies parts of California, Nevada, Arizona, and Utah between roughly 2,000 and 6,000 feet. It functions as a marker of the Mojave Desert zone and provides cover and resources for many desert animals.

Major threats include habitat loss, warming temperatures, reduced precipitation, and wildfire driven by invasive grasses. Low elevation sites show low seedling survival, and even high elevation refuges have been damaged by recent fires such as the 2020 Covington Flats burn.

Conservation work focuses on seed banking, habitat protection, fuel management, and research on shifting the species into cooler zones. The Mojave Desert Land Trust has assembled large seed collections, and in 2023 California enacted the Western Joshua Tree Conservation Act to support long-term protection.

Joshua trees hold cultural importance. The name was given by Mormon pioneers, and Native groups such as the Cahuilla used the plant for tools, fiber, and food. Continuing research and management aim to maintain the species across its natural range.

photo of Joshua trees in Mojave Desert