The iconic Joshua Tree (Yucca brevifolia) is the treasure of the Southern California high desert. The Joshua Tree is found in the Mojave Desert, which stretches from southeast California into parts of Arizona, Nevada, and Utah. Joshua Trees were named by the Mormons settlers in the early 1800s. The outstretched branches of the trees reminded the Mormons of their prophet, Joshua. Today, the Joshua Tree National Park is where the Mojave and Colorado desert ecosystems meet and where we go to see the strangely beautiful looking Joshua Trees.
The Joshua Tree is part of the agave family. It can grow up to 40 feet and life spans of 150 to 200 years! Because the Joshua Trees are only found in the Mojave Desert, the health of the Joshua Trees are big indicators of the health of the Mojave Desert ecosystem. The survival of the trees exclusively depend on the Yucca Moth for pollination and the Yucca Moth depend on seeds of Joshua Trees for nourishment for the larvae. This special relationship between the two species is the key to thriving!
Joshua Trees can be found in Joshua Woodlands SEA and Antelope Valley SEA located in northeastern Los Angeles County. There is a pocket of Joshua Tree woodlands uncharacteristically growing in northwestern LA County, which is outside of the Mojave Desert range. This pocket is also designated as part of the Joshua Woodlands SEA. The resiliency of these trees can be seen after a wildfire. New growth can be seen sprouting from the base of burnt trunks of Joshua Trees.
Joshua Trees are vulnerable because of its limited range where it can grow and reliance on the Yucca Moth for reproducing. Well-timed rains are important for the growth of seedlings and winter freezes stimulate flowering. Threats to the Joshua Trees are wildfires, droughts, rising temperatures are detrimental to these unique trees that call Southern California its home.
Pictures: Joe Decruyenaere, Dan Hoffman
References: Access Science, National Park Service, Joe Decruyenaere