Some tropical plants like maize, sugarcane, many grasses, sorgam, millet, many plants of asteraceae, many plants of brassicaceae etc show a special type of photosynthesis called C4 cycle or C4 pathway. In this type of pathway, the first product of carbon dioxide fixation (malic acid or aspartic acid) is formed in the cells of mesophyll. It is a 4 carbon compound.
Malic acid is transferred to the bundle sheath cells where it is converted into pyruvic acid. Pyruvic acid then takes part in the C3 cycle or Calvin cycle.
