The genus Ammopiptanthus, endemic to the eastern desert of Central Asia, includes two species: A. mongolicus (Maxim.) Cheng f. and A. nanus (M. Pop.) Cheng f. Ammopiptanthus is the only genus of evergreen broadleaf shrub in the northwest desert of China and both species are dominant in the local vegetation, so this genus plays an important role in fixing moving sands and delaying further desertification. The biological property of Ammopiptanthus evergreen broadleaf has been viewed as an ancestral trait that identifies it as a Tertiary relict taxon. The vegetation in northwest China was dominated by evergreen and/or deciduous broadleaf forests in the early Tertiary period according to the fossil evidence. When subsequent changes made the climate colder and drier from the early Miocene (24–1