Unlike most flowering plants that attract bees and butterflies, the Joshua tree only pairs with the Yucca moth throughout its long lifespan, which can last hundreds to even 1,000 years.
If you’ve ever visited the Mojave Desert in the United States, you certainly couldn’t take your eyes off the Joshua trees with their long, sharp leaves resembling spears. Against the barren backdrop of rocks and sand, they stand out, both intimidating and stunningly beautiful.
Native to the Southwestern United States
Joshua, scientifically known as Yucca brevifolia, is endemic to the Mojave Desert, growing at elevations between 400 and 1,800 meters. With long, narrow, stiff, and sharp leaves, this tree is also known in Spanish as Izote de desierto, meaning “desert dagger.”
The Joshua tree is native to the Southwestern United States.
The name Joshua was given in the 19th century by Mormon settlers. The shape of this tree evokes the image of Joshua, the biblical figure who raised his hands to guide the Israelites during their conquest of Canaan.
The Mojave Desert, famous not only for its extreme aridity but also for the renowned Death Valley, is the only sanctuary for Joshua trees in the world. Additionally, this desert supports between 1,750-2,000 other plant species.
The name Joshua was given in the 19th century by Mormon settlers.
The World’s Slowest Growing Tree
Climbing to over 400 meters above sea level in the Mojave, you will be greeted by a forest of Joshua “dagger leaves.” Each leaf can grow from 15 to 35 cm long, but only about 7 to 15 mm wide, resembling sharp blue-green blades.
Not only are the leaves long and sharp, but their edges are also serrated. Interestingly, from February to late April, this seemingly hostile plant produces stunning flower clusters. However, these flowers do not bloom annually; their development depends on the desert’s rainfall conditions and the right timing.
Flowers of the Joshua tree.
Normally, a young Joshua tree will only grow a single stalk. It is only when it matures and is about to flower that it begins to branch out. However, if the main stalk is damaged for any reason, it will quickly grow new branches to replace it.
A remarkable aspect of the Joshua tree is its extremely slow growth rate. In the first 10 years, a Joshua tree grows only about 7.6 cm per year. From the 11th year onward, its growth slows even further to about 3.8 cm per year.
The reason for this slow growth is its harsh living environment. Since Joshua trees grow in the desert, even after successfully dispersing seeds, they must “watch the sky, watch the earth, watch the clouds” before they can germinate. Only when they receive the rare rainfall will the Joshua seedlings break through their shells. If any seeds germinate prematurely without rain, they will never branch out or flower.
Joshua grows very slowly.
However, in contrast to its slow-growing trunk, the root system develops early and extends deep into the ground. It can reach up to 11 meters away from the trunk. From these roots, some young Joshua trees can also sprout, creating a growing “family.”
Overall, a Joshua tree can live for hundreds of years, even up to 1,000 years. However, despite their advanced age, they do not grow much taller, typically reaching heights of only 15 to 20 meters.
A Joshua tree can live for hundreds of years, even up to 1,000 years.
For desert animals, the Joshua tree serves as a perfect sanctuary. Scott’s orioles enjoy building nests in its branches, while rodents choose the base of the Joshua tree to dig burrows. Many other animals find shade under its canopy to escape the scorching sun.
Faithful Only to the Yucca Moth
Like all flowering plants with stamens and pistils, Joshua trees also require pollinating insects. However, they exclusively attract the Yucca moth.
The Yucca moth may not have an eye-catching appearance, but surprisingly, this moth has developed a unique proboscis instead of the usual pointed tongue. This adaptation allows it to easily pollinate the Joshua tree. In return, the tree allows the moth to lay its eggs in its flowers. The Yucca larvae, upon hatching, will feast on the young Joshua fruit.
The reason Joshua trees take the risk of relying entirely on the Yucca moth is that they produce flowers without nectar. Most insects that linger around flowers are drawn by sweet nectar rather than beauty. The Yucca moth, in particular, doesn’t visit Joshua flowers for food; it comes to lay eggs.
Each Yucca moth visiting a Joshua flower will use its tentacle-like mouth to form the pollen into tiny balls.
In fact, without the Yucca moth, the Joshua tree cannot reproduce. Each Yucca moth visiting a Joshua flower will use its tentacle-like mouth to shape the pollen into tiny balls. It then carries these “pollen balls” to another Joshua flower that hasn’t had eggs laid in it by a fellow moth, ensuring the next generation while simultaneously pollinating the Joshua tree.
When the Yucca larvae hatch, they will consume the young Joshua fruit. Once mature, they crawl down to the base, burrow into the ground, build cocoons, and wait for the following spring to continue the cycle.
As for the Joshua tree, it will focus on nurturing the fruits that are not eaten by the Yucca larvae. When the fruits ripen, wind or wildlife will help disperse the seeds.
