The Mormons named the tree for the Biblical figure Joshua, or so the story goes.
Joshua, who played somewhat of an Assistant to the General Manager, that being Moses, raised his hands skyward to the Lord in the good old days. Subsequently, when continent-crossing Mormons reached the southwestern corner of the nation, they came across these tree-sized yuccas reaching with their long sharp leaves to the sky and figured they must be the plant reincarnate of the Old Testament wise-man.
Their leaves tend to be described as massive daggers more often these days than praying hands, but whether a metaphor for war or a holy man, the trees are impressive in their unusualness. As a yucca, living of their own accord somewhere between desert cacti and forest tree, the beauty comes as much from their unusualness as it does their physical appearance.
Standing in troves on hillsides and valleys as we cross the Mojave, they disappear at times and then show up a few towns later as though they know some backroad shortcut. Like a real cowboy, they look best in silhouette at sunset, or under the haze of a thick desert heat.