The Joshua Trees reach somewhere around 30 feet tall and are very slow growing. Grown only in the Mojave desert, they are protected. Their partner is the Tegeticula, a moth that pollinates its flowers. In fact, this particular tree has a relationship only with this type of yucca moth. And the reverse, the yucaa moth pollinates no other plant. The trees bloom March to May.
I photographed this bloom last year in March while driving to Upland California from Bakersfield. My drive was the long way across the mighty desert. I miss it so.