Description

The Joshua tree is emblematic of California’s Mojave Desert. Its range extends to the surrounding mountains into Nevada, Utah, Arizona and Baja, Mexico. An easy place to see this peculiar tree is along California’s Interstate 5 as it crosses the Tejon Pass. This is the western limit of its range. Another plant community where the Joshua tree is prevalent is the juniper/pinon pine woodlands along Highway 18 near Big bear. The Joshua tree is one of several members of the agave family, Agavaceae, in California. Somewhat surprising, this family includes the camas lily and soap plant. All members share a rosette of linear leaves. The Joshua tree has short leaves (“brevifolia”)relative to its local relatives the Mojave yucca, Yucca shidigera, and banana yucca, Yucca baccata. For many years a Joshua tree will consist of a little cushion of these spiky leaves. As the years progress, it takes on a columnar form topped with a tuft of new growth. The old leaves fold down along the trunk, giving it a shaggy appearance. This will be the growth pattern for several decades. At five feet in height or so, a Joshua tree will begin to branch. Very old trees will begin to shed the dry leaves to reveal a rough bark. A mature plant will produce a conical cluster of large white flowers in spring. Joshua trees grow about three inches a year under optimal conditions. This tree will grow in the SF Bay Area in gritty, well-draining soil and full sun. Iti perhaps will grow best in a large container against a south-facing wall.