Its boundaries are generally noted by the presence of Joshua trees and it is believed to support an additional 1,750 to 2,000 species of plants .
Joshua trees are native only to the Mojave Desert and are considered an indicator species .
Its boundaries are generally noted by the presence of Joshua trees , which are native only to the Mojave Desert and are considered an indicator species , and it is believed to support an additional 1,750 to 2,000 species of plants .