Nov 13, 2023 · By Erik Olsen

The Joshua Tree Isn’t Really a Tree, and Its Future Isn’t Certain

The Mojave’s signature plant is a giant yucca that depends on a single moth to reproduce. Here’s how Joshua trees got their name, why they’re so hard to age and why fire and heat threaten them.

Updated Oct 12, 2026

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The first time you see a Joshua tree, it doesn’t look real. It’s shaggy, it’s spiky and its arms go off in every direction like something Dr. Seuss would draw. It’s the signature plant of the Mojave Desert, and it’s also not really a tree.

The Joshua tree (Yucca brevifolia) is a giant yucca (more here). It’s usually grouped with the agaves, and it’s more closely related to asparagus than to an oak or a pine. It has a thick, shaggy trunk and clusters of stiff, spiky leaves at the ends of its branches. It also doesn’t make growth rings, which makes it hard to tell how old one is. They can live for hundreds of years, and some are thought to be more than a thousand years old. The tallest reach about 49 feet. New Joshua trees grow from seed, and in some places they also sprout from underground stems spreading out from a parent tree.

Joshua Tree National Park (Erik Olsen)

In Spanish it’s called izote de desierto. Science first described it as Yucca brevifolia in 1871, when the botanist George Engelmann wrote it up as part of the Wheeler Survey, a government expedition mapping the American West.

The English name supposedly comes from Mormon pioneers crossing the Mojave in the mid-1800s. The story goes that the tree’s raised, outstretched arms reminded them of Joshua in the Bible, holding up his arms during the Israelites’ conquest of Canaan, with the shaggy leaves as his beard.

It’s a great story, but there’s no record of anyone telling it at the time. The name “Joshua tree” doesn’t show up in writing until well after the Mormons settled the area, and nobody really knows where it came from.

Joshua Trees burned in the 2020 Dome fire. (Photo: Erik Olsen)

Joshua trees live almost entirely in the Mojave, the smallest and driest desert in North America, mostly between 2,000 and 6,000 feet, where nights can drop below freezing and days get very hot.

They can’t reproduce on their own. Joshua trees are pollinated only by yucca moths, which lay their eggs inside the flowers and pollinate them in the process. The moth larvae eat some of the seeds, and the rest grow into new trees. Neither one could survive without the other.

Joshua Tree National Park was set up as a national monument in 1936, thanks to local people who wanted to protect the trees and the desert around them, and became a national park in 1994.

The trees anchor a whole community. By some estimates, their roots can reach as far as 30 feet down and 36 feet out in search of water. Birds like Scott’s oriole nest in the branches, and black-tailed jackrabbits rest in their shade. Biologists consider them a keystone species for the high desert.

Joshua Trees burned in the 2020 Dome Fire (Photo: Erik Olsen)

Their future is shaky. Climate change is making the desert hotter and changing when and how much it rains, and projections show the area where Joshua trees can survive shrinking by as much as 90 percent by the end of the century.

Fire is the other threat. In August 2020, the Dome Fire burned more than 43,000 acres of the Mojave National Preserve, including much of Cima Dome, one of the densest Joshua tree forests in the world. An estimated 1 million to 1.3 million Joshua trees were killed.

Joshua Trees burned in the 2020 Dome Fire (Photo: Erik Olsen)

I walked through the burn at Cima Dome after the fire, and the photos here are from that trip.

Joshua trees didn’t evolve with frequent fire, and they don’t recover from it well. The desert now has more invasive grasses that carry flames from plant to plant, and hotter, drier years make it harder for burned forests to come back. Cima Dome may never look the way it did.

California climbed out of drought in 2023, but nobody expects the heat to let up. If the hot, dry trend continues, Joshua trees could lose 90 percent of their range by 2100, Dr. Cameron Barrows, a research ecologist at UC Riverside’s Center for Conservation Biology, told Outside magazine.

If you haven’t seen them, go. There are still plenty of Joshua trees out there, and they’re still as strange as ever.