C4 plants show kranz type of anatomy. In kranz anatomy, the mesophyll is undifferentiated and its bundle sheath cells occur in concentric layers around vascular bundles. First stable product in C4 plant is OAA (oxaloacetic acid). OAA is reduced to malic acid in mesophyll cells. There is little loss of photosynthetic activity on account of photorespiration as it is absent in C4 plants. In C4 plants, photosynthesis is appreciable even under water stress