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.
Hardiness (plants) water to freeze between cell walls and the cells to survive. Plants normally considered hardy may not survive freezing if they are not readily acclimated, which renders them unable to use these mechanisms. Various hardiness ratings are published. In the USA, the most widely used is the USDA system of hardiness zones based on average minimum yearly temperatures. This system was developed specifically for the extremely diverse range of conditions in the United States (US), from baking desert to frozen tundra. Another commonly used system is the Sunset Climate Zone system . This system is much more specific to climates