Joshua Trees - National Park Service

Surrounded by twisted, spiky trees that look like something from a Dr. Seuss book, you might find yourself wondering—where are we? The traveler pulls over for a snapshot of this peculiar plant. The naturalist reaches for a field guide to decode its mystery. The rock climber, brushing past its dagger-like spines, yelps, “Yowch!”

What Is a Joshua Tree?

The Joshua tree (Yucca brevifolia) is the namesake of Joshua Tree National Park and a defining feature of the Mojave Desert. Once classified as a giant lily, modern DNA research has placed it in the Agave family. Like the California fan palm (Washingtonia filifera), the Joshua tree is a monocot—part of the same botanical group that includes grasses and orchids.

At first glance, it’s easy to confuse Joshua trees with their close relative, the Mojave yucca (Yucca schidigera). A key difference? The Mojave yucca has longer, broader leaves with fibrous threads along the edges.

While the Joshua tree is an iconic indicator of the Mojave Desert, it can also be found growing alongside saguaros in the Sonoran Desert of western Arizona or among pines in the San Bernardino Mountains.

A Tree of Many Names

Long before settlers arrived, Native American communities recognized the Joshua tree for its many uses. The Cahuilla people, for example, referred to it as hunuvat chiy’a or humwichawa. Its tough leaves were woven into baskets and sandals, while its flower buds and seeds (either raw or roasted) were valuable food sources.

In the mid-19th century, Mormon settlers gave the tree its common name, believing its outstretched branches resembled the biblical Joshua guiding them westward. However, historical records offer little evidence for this tale. Some theories suggest that pioneers saw the tree as a symbol of Joshua’s military leadership, its sharp leaves evoking the image of an armed force.

A Survivor of the Desert

Joshua trees are uniquely adapted to thrive in the arid, extreme conditions of the high desert. Their life cycle begins with the rare germination of a seed, often sheltered by the protective branches of a neighboring shrub. Growth is slow—after a brief early spurt, they settle into a steady pace of about ½ inch to 3 inches per year. The tallest Joshua trees in the park stretch over 40 feet into the sky, and while the average lifespan is thought to be around 150 years, some may be far older.

Unlike traditional trees, Joshua trees don’t form growth rings, making age estimation difficult. Instead, researchers estimate age based on height and growth rate.