"You better get down there fast," Olroyd said. "It won't last long."
In fact, the rare occurrence has most likely already peaked.
"This is a once-in-a-lifetime phenomenon," Cameron Barrows, a research ecologist with the University of California, Riverside, told the Riverside Press-Enterprise.
Theories for the massive blooming include late-summer storms in 2012, two years of drought, and stress due to global climate change.
Tony Frates, conservation co-chairman of the Utah Native Plant Society, said the blooming around the Joshua Tree National Landmark in Washington County near the Arizona border likely started around March 1, "so they may now be nearing end of their bloom cycle, or could even be past it at this point."
Joshua trees of up to an estimated 1,000 years old have been found in California and are also unique in that moths are their main pollinators.
Yucca brevifolia, the scientific name, earned the common name Joshua tree, as the story goes, when Mormon pioneers crossed the Mojave Desert sometime in the mid-1800s.
Apparently, the trees reminded the pioneers of Joshua from the Bible reaching his hands to the sky while praying.