For scale this branch and flower is about 30" wide, the tree had 11 flowers and was 20' tall making it between 500 and maybe 1,000 years old. I took the photo last week in the Joshua Tree Byway area which borders Nevada, Utah & Arizona.
About the tree: First, they are not a tree but a Yucca plant that happens to resemble the size and growth pattern of a tree. They grow a fairly limited range within the Mojave Desert of California, Nevada, Utah, and Arizona. They only grow between elevations of 2,000 and 6,000 feet. They tend to grow from 15 to 40 feet tall, usually only adding 2 to 3 inches each year. It will take around half a century for a Joshua Tree to reach full size. Wikipedia