C4 plant or Hatch-Slack cycle was proposed by MD Hatch and CR Slack (1966). In Hatch-Slack pathway, first product of CO3 fixation is a 4 carbon compound, oxaloacetic acid, that is why it is called C4− plant. This cycle takes place mostly in monocot plants like Artiplex, sugarcane, maize, Cyperus and in some dicots (Amaranth us).