Yucca brevifolia jaegeriana is found in the eastern Mojave Desert. This species is smaller and tends to be denser, has smaller leaves and can branch before its first flowering. Excellent populations can be found within the Mojave National Preserve and near Dolan Springs, Arizona. The Joshua tree grove at Cima Dome, again in the Preserve, is considered one of the densest and largest in existence. Until the creation of Mojave National Preserve no population of Yucca brevifolia jaegeriana was protected.
Germination is associated with abundant winter precipitation.
Grazing animals from cows and deer down to small rodents usually eat the young Joshua sprouts, so most trees begin life in the protective canopy of a bush. After several years of growth the dagger like leaves provide protection, and eventually it grows up and out of the protector plant. Mature plants produce beautiful white flowers, and a good Joshua tree bloom is one of the delights of the desert. An interesting example of mutual dependence exists between yucca moths and Joshua trees. Like other yucca, Joshua trees are only pollinated by a specific species of yucca moth, so each are dependent on the other for survival.