The nation­al park is made up of two dif­fer­ent deserts: the south­ern end of the Mojave Desert forms its west­ern edge, while the Col­orado Desert cov­ers its east­ern and south­ern por­tions. As such, the Joshua trees for which the park is named are more com­mon in the high­er ele­va­tions on the Mojave side, but here’s the fun­ny thing: they’re not actu­al­ly trees. The plants are mem­bers of the Yuc­ca genus and can grow up to 70 feet tall, though they can take up to 50 years to reach their full size.