Even though very few cells in a C₄ plant carry out the biosynthetic – Calvin pathway, yet they are highly productive. This is because of the following reasons: (a) C₄ plants have a high value of net assimilation at high temperatures. (b) Their rate of carbon assimilation is quite rapid. (c) C₄ plants perform photosynthesis even when stomata are closed. (d) Their rate of net photosynthesis at full sunlight is as high as 40-80 mg CO₂/ dm₂/hr.