ABSTRACT
Phyto-geography is concerned with all aspects of plant distribution, from the controls on the distribution of individual species ranges to the factors that govern the composition of entire communities and floras. There are two major divisions of Phyto-geography: descriptive phyto-geography and Interpretive or dynamic phyto-geography. There are mainly two theories of tolerance and they are ‘General theory of tolerance’ proposed by American zoologist Victor Ernest Shelford in 1911 and ‘Specific theory of tolerance’ proposed by Good. The most prevalent group of crops across the world is cereals. All living organisms on earth are going to react with environmental stimuli and in doing so they show differences in their behavior, morphology, anatomy, physiology and reproduction structures. Such changes which enable the organism to withstand the atrocities of environment and utilize it to their maximum benefit are known as adaptations.
