A Joshua Tree
Joshua trees are a relative of the Yucca plant (another name for them is Yucca Palm) which is also very abundant in the desert here. The park has relatively flat desert areas with hundreds of these trees, then, for no apparent reason, the area transitions to plain desert with no trees, just other usual desert plants of yucca, creosote, sage, etc.
The name Joshua tree was given by a group of Mormon settlers 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 in prayer.