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.
Halophyte only 2% of all plant species. The large majority of plant species are glycophytes, which are not salt-tolerant and are damaged fairly easily by high salinity. Halophytes can be classified in many ways. According to Stocker (1933), it is mainly of 3 kinds, viz. 1. Aqua-halines 2. Terrestro-halines 3. Aero-halines Again, according to Iversen (1936), these plants are classified with respect to the salinity of the soil on which they grow. 1. Oligo-halophytes (amount of NaCl in the soil is 0.01 to 0.1%) 2. Meso-halophytes (amount of NaCl in the soil is 0.1 to 1%) 3. Euhalophytes (amount of NaCl