Facts About the Joshua Tree
The iconic Joshua tree plant has captivated the imaginations of all those who have encountered it. Though once described as “the most repulsive tree in the vegetable kingdom,” their unique appearance draws thousands of visitors to Joshua Tree National Park every year, and has even been a source of artistic inspiration. These days, though, it is facing increasing pressure due to climate change.
Here are 22 facts about the Joshua tree.
The Joshua Tree is Not a Tree
What is the Joshua tree? Don’t be fooled by the name – the Joshua tree is not actually a tree!
This iconic part of California desert vegetation is a type of grass-like flowering plant called a monocot. It goes by many names, like the yucca palm, tree yucca and palm tree yucca, but its scientific name is Yucca brevifolia.
Until recently, the Joshua tree was considered a member of the lily family. The lily family has now been split into 40 separate plant families, and the Joshua tree has found its rightful place in the agave family.
Despite the similarity – in both name and appearance – don’t confuse the Joshua tree with the Mojave yucca, Yucca schidigera. Though they also share the same habitat, the yucca plant has longer, wider leaves compared to the Joshua tree, with fibrous threads that curl along the leaf edges.
Why Does the Joshua Tree Have Such a Unique Shape?
The Joshua tree has a very unique shape with a top-heavy branch system. Typically, Joshua trees develop a dense crown of branches growing out of a single stem. The branches develop after the tree blooms.
Ever noticed some Joshua trees growing straight up, with no branches? These trees have never bloomed!
There May Actually Be Two Different Types of Joshua Trees
Close study of the Joshua tree has led some botanists to advocate that the species be split in two. They have noticed a distinct difference in the trees that grow in the western Mojave desert, compared to those in the eastern Mojave.
The western Joshua trees are taller and more “tree-like” with longer leaves and a taller trunk topped with that characteristic crown of branches. On the other hand, the eastern Joshua tree tends to be shorter and more “bush-like”. They have shorter leaves and more branches, with a shorter trunk.
These botanists would classify the western Joshua trees as the “classic” Yucca brevifolia, while they name the eastern ones Yucca jaegeriana. What an interesting fact about the Joshua tree!
How Did the Joshua Tree Get its Name?
Its characteristic shape may also have had something to do with how the Joshua tree got its name!
As the story goes, in the mid-19th Century, a group of Mormon settlers were making their way across the Mojave desert when they came upon the Joshua tree. The outstretched arms of this piece of California desert vegetation reminded them of the biblical story in which Joshua holds out his hands to guide the Israelites across Canaan. In the same way, the Joshua tree guided the Mormons across the US desert, inspiring the name.
Although this is an unconfirmed account of how the Joshua tree got its name (the first written account of the Joshua tree – referred to there as a “yucca tree” – is considered to be from 1844; it seems the term “Joshua tree” wouldn’t be used in California for another 75 years after that), it’s a pretty captivating story.
How’s that for a fun fact about the Joshua tree?
Facts About Joshua Tree: Early Settlers Thought They Were Ugly!
Here’s some more Joshua tree history. Early accounts by white settlers of the Joshua tree almost universally disparaged the Joshua tree as being ugly.
John C. Frémont of the US Army Corps of Topographical Engineers was the first settler to write about the Joshua tree in 1844: “…their stiff and ungraceful form makes them to the traveler the most repulsive tree in the vegetable kingdom.”
In 1919, Los Angeles writer Francis M Fultz wrote about the Joshua tree in Scientific American: “Whenever I see the Joshua-Trees I think how considerate they have been in choosing to make their home where few men have a desire to live.” Ouch!
That same year, Joseph Smeaton Chase had this to say about the Joshua tree, which he wrote about in his book, California Desert Trails:
One can scarcely find a term of ugliness that is not apt for this plant. A misshapen pirate with belt boots hands and teeth stuck full of daggers is as near as I can come to a human analogy. The wood is a harsh, rasping fibre; knife blades long hard and keen fill the place of leaves; the flower is greenish white and ill smelling; and the fruit a cluster of nubbly pods, bitter and useless. A landscape filled with Joshua trees has a nightmare effect even in broad daylight: at the witching hour it can be almost infernal.
The Joshua Tree Was Made Famous by a Rock Band!
These days more people are charmed by the Joshua tree’s appearance, and find inspiration in the desert landscape it calls home. Widespread fascination with the Joshua tree arguably began with U2, a famous Irish rock band. U2’s landmark Joshua Tree album was released in 1987, sparking a wave of global interest in the Joshua tree plant and its namesake park.
Adam Clayton, the bass guitarist for U2, described the group’s desert influence in the following way,
The desert was immensely inspirational to us as a mental image […] Most people would take the desert on face value and think it’s some kind of barren place, which of course is true. But in the right frame of mind, it’s also a very positive image, because you can actually do something with blank canvas, which is effectively what the desert is.
(Although – fun fact! – the iconic Joshua tree photo featured on U2’s album was not photographed in Joshua Tree National Park! But another famous rock group – The Eagles – did shoot their earlier album cover in the famous park.)
Facts About the Joshua Tree: They Only Grow in One Place in the World
Joshua tree plants are found exclusively in the southwestern United States (including Arizona, Southern California, Nevada and Utah) and northwestern Mexico, mainly in the Mojave Desert. In fact, it is considered an indicator species for the Mojave Desert – that is, if you spot a Joshua tree, chances are you’re in the Mojave Desert!
25,000 years ago, the Joshua tree had a far wider range than it does today. Its habitat likely stretched from Death Valley in California all the way south to the Colorado River delta in Mexico. Back then, the landscape looked very different than it does today.
Later, as the ice age ended, a warmer, drier climate took hold in the Southwest. Rivers and lakes dried up and the forests largely disappeared. Joshua trees survived by moving slowly to cooler, higher elevations, their range narrowing.
Today, the Joshua tree plant is most prevalent in the open grasslands of Queen Valley and Lost Horse Valley in the Joshua Tree National Park, though it can also be found in the Sonoran Desert in western Arizona and the San Bernardino Mountains in California.
They Only Grow at Certain Altitudes
Here some more facts about the Joshua tree: they only grow at elevations between 400 and 1800m (1300-5900 ft).
They prefer these higher elevations where the climate is cooler. You’ll find them mostly on slopes, ridges and flat-topped hills of the desert.
Joshua Tree Facts: They Have Been Around a Very Long Time
Joshua trees have existed for 2.5 million years and have experienced many climatic changes. 25,000 years ago, the Mojave “Desert” was rainy, and blanketed by forests, freshwater lakes and rivers.
It was also home to a wide range of animals. At that time, the Joshua tree lived side by side with mammoths, ground sloths, and saber-toothed cats! In fact, in that early time it may have been the giant Shasta Ground Sloths who were responsible for helping to spread Joshua tree seeds.
Facts About the Joshua Tree: They Can Live up to 1000 Years
Estimating the age of a Joshua tree can be a real challenge given that it does not produce the annual growth rings that actual trees do. Instead, scientists can estimate a Joshua tree’s age by looking at its height.
Using this approach, most people estimate that Joshua trees live 150-200 years on average; it isn’t even considered mature until it reaches 60!
Though most Joshua tree plants live to be 200 years old at the most, some have been known to live for as many as 500 years. The oldest recorded Joshua tree lived to be an astonishing 1000 years old!
How Fast Does the Joshua Tree Grow?
On average, Joshua trees grow at a rate of ½ to 3 inches per year. This is considered fast for desert vegetation, though it is slow compared to other plants.
It seems that new Joshua tree seedlings may grow faster in the beginning (as much as 3 inches per year in the first 5-10 years), and then slow down as they mature, growing just 1.5 inches per year after that. At this rate, it will take a Joshua tree 50-60 years to reach its full height. This is when it is considered “mature”.
Joshua Tree Facts: It Can Clone Itself!
One of the most fascinating facts about the Joshua tree has to do with its complex root system.
As a monocot, the Joshua tree has a fibrous root system. The thin roots grow out in a radial pattern from the base of the plant. A typical Joshua tree plant has so many roots – hundreds! – it creates a root system so dense that neighbouring plants most often won’t survive.
Some roots reach deep underground – as much as 10-30 ft (3-9m) – in search of water in the dry desert. Other roots grow laterally, only 1-6 inches (2.5-15cm) deep.
Called rhizomes, these roots produce new shoots of genetically identically clones of the original Joshua tree! Being able to clone itself can be an evolutionary advantage, allowing a Joshua tree population to recover more quickly in times of disaster like floods or fires.
In some areas, cloning seems to be the primary way the Joshua trees reproduce. Elsewhere, they rely on wind or small animals who eat their fruit and then disperse its seeds across the desert.
Facts About the Joshua Tree: How Big Are Joshua Trees?
Joshua trees are tiny when compared to actual trees, but grow fairly large compared to most California desert vegetation. The tallest Joshua trees grow as tall as 15m (49 ft) and 30-100cm (1-3 ft) in diameter.
While they make for a grand presence in the desert, compare this to the average pine tree (45m/150 ft) or the towering redwoods (over 90m/300 ft)!
The Joshua Tree Produces Flowers – And They Smell Really Bad!
When a mature Joshua tree blooms, it produces whitish-green or creamy yellow flowers. These flowers are bell-shaped and arranged in clusters. They are pretty nice to look at but don’t get too close! Unlike most flowers, the Joshua tree flowers produce a very unpleasant smell. This is one flower you don’t want to stop and smell!
It Also Produces Fruit
In addition to its foul-smelling blooms, the Joshua tree produces a fleshy fruit. This fruit is green or brown in colour, oval shaped and filled with seeds. Small rodents can climb the tree to eat the fruit before it dries up and falls to the ground. That’s one way the seeds can be dispersed. The wind may play another role, blowing the seeds around once the fruit has fallen to the ground.
You’re Lucky if You See a Joshua Tree in Bloom
Have you seen a Joshua tree in bloom? If so, count yourself among the lucky ones! They do not necessarily bloom every year. The Joshua tree will bloom between February and April – but only during years where there has been enough rain. Not only that, they are only able to bloom after a winter freeze. These are very picky plants!
Joshua Tree Significance for Indigenous Cultures
One of the most interesting facts about the Joshua tree is its traditional significance for Indigenous cultures of the area.
Prior to the arrival of Europeans in 1769, the area now known as Joshua Tree National Park was inhabited and used by the Serrano, Cahuilla, Mojave, and Chemehuevi Indigenous nations. In the traditional Cahuilla language the Joshua Tree is known as hunuvat chiy’a or humwichawa.
These Indigenous people used the Joshua tree for many purposes: baskets and sandals could be woven from the tough Joshua tree leaves, while flower buds and seeds were consumed (raw or roasted) as part of their traditional diet.
In addition, the Joshua tree’s branches could be removed, their interior scraped out, and the remaining hollow limb used as a canister to carry nuts and berries. They also used the tree’s reddish rootlets to create a natural dye for decorating their woven baskets.
Facts About the Joshua Tree: The Joshua Tree Used to be a Source of Paper
Yep, that’s right: as far back as 1883, Joshua tree pulp was used by the London Daily Telegraph to make paper.
They Play an Important Role in the Ecosystem
Another of the more unique facts about the Joshua tree is how important it is to the desert ecosystem in which it lives.
Joshua trees provide food and shelter for a number of mammals, birds, reptiles and insects. Red-shafted flickers drill holes in the branches to make nests which can be later occupied by other birds, too. Desert night-lizards live in the Joshua tree’s dead leaves and branches. Another example are the woodrats who gnaw off the spiny leaves with which to make their nests.
The Joshua Tree & Moths: A Symbiotic Relationship
Bet you haven’t heard these facts about the Joshua tree!
Joshua trees have a unique co-evolutionary relationship with the Yucca Moth (also known as the Pronuba Moth). The Joshua tree relies exclusively on the yucca moth for pollination. It is the ONLY insect that can pollinate the Joshua tree plant.
As the yucca moths (actually, there are two distinct species of yucca moth, Tegeticula synthetica and T. antithetica, that pollinate the two types of Joshua tree) lay their eggs inside the ovary of the Joshua tree flower, they collect pollen with a pair of long, coiled “tentacles”. They then deposit this pollen in other flowers, resulting in pollination.
But it’s a two-way street. The moths also need the Joshua tree in order to survive! When the moth’s eggs hatch into larvae, these hungry larvae feed on the Joshua tree’s seeds.
Without the Joshua tree, the moths could not make caterpillars. Without the moths, the Joshua trees could not produce seeds. It’s as simple as that.
The Joshua Tree is Threatened by Climate Change
Sadly, Joshua tree adaptations are no match for the fast pace of climate change. If we don’t do anything about it, it is predicted that more than 99% of its habitat could disappear before the end of the century.
>> Click here to read our full post on the Joshua tree and climate change.
What are some of the stressors threatening the Joshua tree’s survival? For starters, hotter temperatures, increasing drought, and the loss of groundwater are taking their toll. The Joshua tree prefers a cool climate – that’s why it tends to be found at higher elevations. Moreover, it needs a cold snap during the winter in order to flower.
In addition to habitat loss, climate change is helping to create more favourable conditions for wildfires, which also spell trouble for the Joshua tree’s survival.
Can the Joshua tree be saved? It’s hard to say. Even if significant action is taken to reduce greenhouse gas emissions, we may only be able to save just under 20% of the Joshua tree’s original habitat.
Are Joshua Trees California Protected Trees?
Losing the Joshua tree due to climate change would be devastating for the environment, and for the people who identify with these plants as part of their home.
Recognizing the threat that climate change poses to the Joshua tree, in 2015 an environmental group (WildEarth Guardians) petitioned the US Fish & Wildlife Service to recognize the Joshua tree as “threatened” under the Endangered Species Act.
Sadly, their application was denied in August 2019, just weeks before the 25th anniversary of Joshua Tree National Park, on October 31st of that year.
In November 2019, WildEarth Guardians took the US Fish & Wildlife Service to court. If you want to help them in their fight to protect the Joshua Tree, you can sign their petition.
Bonus Joshua Tree Facts: There’s a Movie Called “Joshua Tree”!
Yep, that’s right! Joshua Tree is a 1993 action movie starring Dolph Lundgren about an ex-race car driver who turns to a life of crime, transporting stolen exotic cars. It really has nothing to do with the Joshua tree itself other than taking place in the desert. Part of the film was actually shot in Joshua Tree National Park, too!
A Fascinating Plant: So Many Facts About the Joshua Tree!
There are so many interesting facts about the Joshua tree. With its cultural significance, its importance in the ecosystem and its place in popular culture, there is truly no other desert plant quite like the Joshua Tree.
Whether you find its appearance weird, ugly, unique or stunning, the Joshua tree is one of the most memorable desert plants out there. Let’s hope we can keep it around for many years to come.
For more about the Joshua Tree and climate change, check out this post.
Lady Bird Johnson Wildflower Center
The Joshua Tree Genome Project
KCET, a broadcaster in Southern and Central California
The National Park Service
The National Wildlife Federation