Corn, or maize, is a C4 plant. A c4 plant relates to a group of plants that feature 4-carbon molecules present after the first product of carbon fixation.

C3 carbon fixation is one of three metabolic pathways for carbon fixation in photosynthesis, along with C4 and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into 3-phosphoglycerate.

C3 and C4 plants are named after the number of carbon molecules in the first products of their carbon fixation cycles.

C3 plants produce 3-phosphoglycerate and C4 plants produce Oxaloacetate.

C4

They are named after the number of carbons of the first product of their carbon fixation cycle (the cycle used to make plant sugars).

C4 plants have a more elaborate carbon fixation cycle of C3 and reduces photorespiration. They are thought to have evolved more recently than C3 plants.