Atriplex are C-plants, with a characteristic leaf anatomy (kranz anatomy). The genus "Atriplex" is distributed nearly worldwide from subtropical to temperate and to subarctic regions. Most species-rich are Australia, North America, South America and Eurasia. Many species are halophytes and are adapted to dry environments with salty soils. The genus evolved in Middle Miocene, the C-photosynthesis pathway developed about 14.1-10.9 million years ago, when the climate became increasingly dry. The genus diversified rapidly and spread over the continents. The C"Atriplex" colonized North America probably from Eurasia during the Middle/Late Miocene, about 9.8-8.8 million years ago, and later spread to South America.
Plant tolerance to herbivory maximum growth rate (Hilbert et al. 1981). The CCH suggests that there is a continuum of responses to herbivory (Maschinski and Whitham 1989). It predicts that plants growing in less stressful environment conditions, such as high resource or low competition, are better able to tolerate herbivory since they have abundant resources to replace lost tissues and recover from the damage. Plants growing in stressful environments are then predicted to have lower tolerance (Maschinski and Whitham 1989). This recently proposed model takes into account the resource that is limiting plant fitness, the resource affected by herbivory and how the acquisition of