Joshua tree
|
|
- This article is about the tree. For the album by U2, see The Joshua Tree.
| Joshua tree | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Missing image Joshua_tree2.jpg | ||||||||||||||
| Scientific classification | ||||||||||||||
| ||||||||||||||
| Binomial name | ||||||||||||||
| Yucca brevifolia |
Joshua trees (Yucca brevifolia) are monocotyledonous trees found only in North America in the states of California, Arizona, Utah, and Nevada. Confined mostly to the Mojave Desert between 600-1800 m (2,000-6,000 feet), they thrive in the open grasslands of Queen Valley and Lost Horse Valley in Joshua Tree National Park.
Joshua trees can grow from seed or from an underground rhizome of another Joshua tree. They are slow growers: new seedlings may reach a height of 10-20 cm in their first few years, then only grow about 10 cm per year thereafter. The trunk of a Joshua tree is made of thousands of small fibers and lacks annual growth rings, making it difficult to determine the tree's age. This tree is not very sturdy because of its shallow root area and top-heavy branch system. But, if it survives the rigors of the desert, it can live a couple hundred years. The tallest tree in the park is about 13 m (40 feet) tall.
Jtreebloom.jpg
One of the most beautiful spectacles in spring is the creamy white blossoms of flowering Joshua trees. These flowers appear from February to late April. Joshua trees do not branch until after they bloom, and they don't bloom every year. Like most desert plants, their blooming is dependent on rainfall at the proper time. They also need a winter freeze before they will bloom.
Once they bloom, the trees are pollinated by the yucca moth, which spreads pollen while laying her eggs inside the flower. The moth larvae feed on the seeds of the tree, but enough seeds are left behind to produce more trees.
The name Joshua tree was given by a band of Mormons who crossed the Mojave Desert in the mid-19th century. The tree's unique shape reminded them of a Biblical story in which Joshua reaches his hands up to the sky.
 |
Missing image Joshtree.jpg A Joshua tree silhouetted by a rock in Joshua Tree National Park |
|
Missing image California_Scottys_Mountains_Joshua_tree.jpg Joshua trees in winter |
Missing image Joshuatree_redrockcanyon.jpg Joshua Tree with Red Rock Canyon in the background |