Joshua trees can be seen in the Mojave desert in the United States.
Not really a tree, the Joshua tree got its name from its tree-like growths. It’s a yucca, a distinctly American evergreen shrub. It grows only in the southwestern United States, in the arid soils of the Mojave desert. Yucca brevifolia, as it is known scientifically, is the largest member of its genus, standing between five and fifteen meters (16.4 feet and 49.2 feet) tall. The Joshua tree has long, straight, dagger-shaped leaves that are about a centimeter (0.39 in) wide at the base and taper to sharp points at the end. The leaves grow in a spiral at the ends of the stems; dead leaves from previous seasons remain on the stem and accumulate under the new growth. When a winter frost occurs and the amount of seasonal rain is sufficient, these trees flower between February and April. Its whitish flowers grow in clusters and give off an unpleasant odor.
Joshua Tree National Park was opened by President Franklin Roosevelt in 1936.
The Joshua tree reproduces in an exclusive and mutually beneficial arrangement with the female Yucca moth, whose organs are uniquely capable of collecting and transferring the tree’s pollen. The moth helps the tree reproduce as it completes its own reproductive cycle: it collects pollen when it lays eggs inside a flower’s ovary. As their eggs hatch, the tree’s seeds grow, and the moth larvae feed on the seeds when they hatch. The larvae usually leave enough seeds for more trees to grow, but the Joshua tree has special features to ensure that the yucca moth hatchlings don’t overeat their welcome: if there are too many moth eggs in one ovary, the tree you can abort it.
The whitish flowers of the Joshua tree give off an unpleasant odor.
In addition to growing from seed, the Joshua tree can grow from the rhizomes of other trees. This type of growth helps the tree survive floods and fires that kill the main tree but leave the root system intact. The tree grows very slowly. During the first few years, seedlings may gain two centimeters (0.79 in) per year, but then they usually only grow one centimeter per year (0.39 in). The trunk of the tree is made of fiber and therefore does not have the growth rings that most other trees have. It also has a shallow root system that must support its disproportionately large and heavy size, making it difficult for it to survive in the desert. Despite this, a Joshua tree often lives for several hundred years.
Mormon settlers are believed to have named the plant after the biblical prophet Joshua. The shape of the tree’s outstretched branches reminded them of the biblical story in which the prophet Joshua stretches out his hands heavenward. Joshua Tree National Park gives the tree another important place in American history: Franklin Roosevelt dedicated the park in 1936 to ensure that California’s rapid urban sprawl did not threaten the unique desert ecosystem where trees are king. .