Why do they call it a Joshua Tree?

Answer 1

According to the website listed below: "When seen first hand they seem to possess a sublime presence and sense of human morphology no more so than when visited on one of those ethereal summer desert evenings or when the trees are cloaked in a winter snow. In fact, according to both Bakker (1971) and Royo (1997), the Joshua tree is said to have got its name from the Mormons who likened it to the prophet Joshua with arms aloft, waving. "

Answer 2

Because a guy named Joshua planted it.