How Did the Joshua Tree Get Its Name?

The Joshua tree almost certainly owes its common name to mid-nineteenth-century Mormon settlers who crossed the Mojave Desert and saw something biblical in the tree’s outstretched, arm-like branches. According to the most widely repeated account, the shaggy silhouette reminded them of the Old Testament figure Joshua raising his hands in prayer to guide the Israelites toward the Promised Land. The story is compelling and deeply embedded in Western American lore, but the historical trail behind it is thinner than most people assume.

The Mormon Legend and Its Gaps

The standard version of the story places the naming sometime in the 1840s or 1850s, when members of the Church of Jesus Christ of Latter-day Saints were migrating westward through the desert toward Utah and California. Seeing the strange trees with their uplifted limbs, the settlers supposedly christened them “Joshua trees” as a spiritual metaphor. The tree, with its twisted branches pointing heavenward, was said to resemble the prophet Joshua beckoning them onward through the wilderness.

The trouble is that no one has found a diary entry, letter, or church record from that era that actually uses the name “Joshua tree.” The earliest documented appearances of the term date to later in the nineteenth century, and they attribute the name to Mormon settlers without citing a specific source. This doesn’t mean the story is wrong. Oral tradition was powerful among pioneer communities, and the name could easily have circulated by word of mouth for decades before anyone wrote it down. But it does mean the origin story sits in a gray zone between plausible folk history and confirmed fact. Historians generally accept the Mormon attribution as the most likely explanation, even while acknowledging it has never been pinned to a specific person or document.

What People Called It Before

Long before any European settlers arrived, the tree had names in multiple Indigenous languages. The Cahuilla people of Southern California used parts of the tree for food, fiber, and footwear. Spanish-speaking explorers and missionaries who encountered the tree earlier gave it descriptive names of their own. One common Spanish term was “izote de desierto,” roughly meaning desert dagger, a reference to the sharp, spiky leaves rather than the tree’s overall shape.

The most colorful early English-language description came from John C. Frémont, the explorer and Army officer who led surveying expeditions across the American West in the 1840s. Frémont encountered Joshua trees in the Mojave and described them in terms that were, to put it gently, unflattering. He called the tree “the most repulsive tree in the vegetable kingdom,” clearly unimpressed by its gnarled limbs and fibrous bark. His reaction captures something important about the Joshua tree’s cultural history: people either find it haunting and beautiful or grotesque and alien. There is rarely a middle ground.

For much of the nineteenth century, settlers and travelers used a grab bag of informal names. “Yucca palm” appeared in some accounts, as did “tree yucca,” both reflecting the plant’s actual botanical identity as a member of the yucca genus. But “Joshua tree” eventually won out, likely because it was more evocative and easier to remember than any taxonomic description. By the early twentieth century, the name was standard enough that when the federal government set aside land to protect the trees, the name was never in question.

The Scientific Name Tells a Different Story

The botanist George Engelmann formally described the Joshua tree in 1871 and gave it the scientific name Yucca brevifolia, which translates to “short-leaved yucca.” That name can feel counterintuitive when you look at a Joshua tree, since its dagger-shaped leaves can reach a foot or more in length. But Engelmann was comparing the tree to other yuccas, some of which have much longer leaves. In that context, “short-leaved” makes sense as a relative descriptor.

The Joshua tree belongs to the family Asparagaceae, making it a distant relative of asparagus, agave, and other desert plants. Despite its name, it is not a true tree in the botanical sense. It lacks the woody growth rings of a typical tree; its trunk is made of densely packed fibers rather than the kind of solid wood you would find in an oak or a pine. This fibrous structure is part of why the Joshua tree has such a distinctive, almost sculptural appearance. Without conventional wood to constrain its growth into regular patterns, branches split and twist in seemingly random directions, each fork the result of the tree flowering and then sending out new shoots.

One Name, Two Species

For over a century after Engelmann’s classification, scientists treated all Joshua trees as a single species. That has changed. Genetic and morphological research now indicates that what people have been calling the Joshua tree is actually two distinct species: the western Joshua tree (Yucca brevifolia) found mainly in the western Mojave Desert, and the eastern Joshua tree (Yucca jaegeriana) found in the eastern Mojave and into parts of Nevada, Arizona, and Utah.¹ The two look similar at a glance, but the western species tends to be taller with longer, more loosely arranged leaves, while the eastern species is typically shorter and more compact.

The split appears to have been driven, at least in part, by the trees’ pollinators. Each species of Joshua tree is pollinated by its own species of yucca moth, and research has shown that the floral traits most closely tied to pollination evolved faster than other features of the plant. In other words, the moths and the trees shaped each other over evolutionary time, and as the moth lineages diverged, the trees diverged with them.² Both species still go by “Joshua tree” in everyday conversation, and most visitors to the Mojave would not notice the difference. But the distinction matters for conservation, since the two species face different threats and may need different protection strategies.

The Moth That Makes It All Work

You cannot talk about the Joshua tree for long without getting to the yucca moth, because the relationship between them is one of the most tightly locked partnerships in the plant world. Joshua trees cannot pollinate themselves. They depend entirely on yucca moths to carry pollen from one flower to another. The moth, in turn, lays her eggs inside the flower, and her larvae eat a portion of the developing seeds. This is an obligate mutualism: neither organism can reproduce without the other.³

The moth’s behavior is remarkable. A female yucca moth collects pollen from one Joshua tree flower, rolls it into a ball, flies to a different flower, lays eggs in the flower’s ovary, and then deliberately pushes the pollen ball into the stigma to fertilize it. She is not doing this accidentally. The entire sequence is an evolved behavior that ensures the seeds will develop and provide food for her larvae. The larvae consume some seeds but leave enough to perpetuate the tree. Yucca moths are widely recognized as one of the most specialized pollinator systems known.⁴

This tight dependency is what makes the two-species question so interesting. The coevolutionary research found that the floral feature most critical to the moth interaction was more differentiated between the two Joshua tree types than any other trait measured, and it matched equivalent differences in moth morphology.² The trees and moths essentially co-speciated, each shaping the other’s evolution. When the moths split into two species, the trees followed, or vice versa. It is a textbook example of how intimate ecological relationships can drive the origin of new species.

How the Name Became a Landmark

The Joshua tree’s transition from a botanical curiosity with a folk name to an American cultural icon happened in stages. In 1936, President Franklin Roosevelt established Joshua Tree National Monument, protecting a large swath of desert in Southern California where the trees grew in dense stands. The monument was upgraded to Joshua Tree National Park in 1994, a change that brought greater federal protection and, eventually, much larger tourist numbers. Today the park draws roughly three million visitors a year, most of whom come at least partly to see the trees that give the place its name.

The name gained a second wave of cultural resonance in 1987 when the Irish rock band U2 released their album “The Joshua Tree,” which became one of the best-selling records in music history. The album’s black-and-white cover photograph, shot by Anton Corbijn in the Mojave Desert, cemented the tree’s image as a symbol of stark, spiritual landscapes. That particular tree, located along a highway in Death Valley, eventually died and fell over, but it remains a pilgrimage site for fans. The album did more to plant the name “Joshua tree” in global consciousness than any botanical guide ever could.

Between the national park and the album, the Joshua tree became shorthand for a certain kind of American desert mysticism. Artists, writers, and musicians have been drawn to the Joshua Tree area for decades, partly for the landscape and partly for the cultural mythology that has built up around it. The tree’s strange silhouette, somewhere between a cactus and something out of a Dr. Seuss illustration, photographs beautifully against desert sunsets and starry skies, making it one of the most recognizable plant images in the world.

A Future Under Threat

The Joshua tree’s name may outlast the tree itself in parts of its current range. Climate modeling projects the elimination of Joshua trees throughout most of the southern portions of their range as temperatures rise. Even where precipitation patterns differ between models, the sheer increase in temperature overwhelms any variation in rainfall, and only a handful of populations within the current range are predicted to be sustainable under future conditions.⁵

The threat is not purely theoretical. Wildfire has already devastated Joshua tree populations in ways that would have been unusual a few decades ago. The Mojave Desert historically did not burn often because there was not enough continuous vegetation on the ground to carry fire. That changed as invasive annual grasses, particularly those stimulated by unusually wet El Niño years, filled the gaps between native plants and created a carpet of fuel. After an El Niño-driven wet year in 1998 produced a boom of invasive plant growth, wildfires swept through parts of what is now Joshua Tree National Park in 1999. By 2004, roughly four out of five burned Joshua trees had died, and even a quarter of unburned trees in the area had succumbed to the prolonged drought that followed.⁶

Joshua trees are slow growers, sometimes taking decades to reach maturity and begin flowering. A single fire can wipe out centuries of accumulated growth in an afternoon, and unlike many fire-adapted species, Joshua trees do not resprout readily from their roots after burning. Each loss is essentially permanent on any human timescale. In 2023, California listed the western Joshua tree as a threatened species under the state’s Endangered Species Act, the first plant ever to receive protection primarily because of climate change. The eastern species, which occupies slightly different habitat in Nevada and Arizona, does not yet have equivalent protection, though the two-species distinction makes conservation planning more complicated than it was when everyone assumed there was just one kind of Joshua tree.

Why the Name Sticks

Plenty of plants have common names rooted in religious or mythological imagery. The passion flower was named by Spanish missionaries who saw symbols of Christ’s crucifixion in its intricate blooms. The burning bush gets its name from its fiery red autumn foliage. But few plant names have achieved the cultural weight of “Joshua tree.” Part of this is simply the tree’s visual drama. It is impossible to drive through a Joshua tree forest and not feel that something unusual is happening in the landscape. The trees look ancient, deliberate, almost animate, as if they froze mid-gesture.

The name also benefits from the fact that the biblical story it invokes is itself about a journey through hostile, arid terrain. Joshua leading the Israelites through the wilderness resonates with the experience of crossing the Mojave, where the trees stand as the most conspicuous living landmarks in an otherwise stark environment. Whether or not a specific group of Mormon settlers actually coined the name on a specific date, the metaphor fits so naturally that it has never faced a serious challenger. No one is lobbying to rename the tree. Even the scientific community, which split the one species into two, kept the common name “Joshua tree” for both. The name has become bigger than its uncertain origin, attached not just to a plant but to a national park, an album, a desert aesthetic, and a particular American idea of wilderness as something simultaneously harsh and sacred.