 The success of the grasses lies in part in their morphology and growth processes and in part in their physiological diversity.Most of the grasses divide into two physiological groups, using the C3 and C4 photosynthetic pathways for carbon fixation.The C4 grasses have a photosynthetic pathway, linked to specialized Kranz leaf anatomy, which allows for increased water use efficiency, rendering them better adapted to hot, arid environments and those lacking in carbon dioxide.