What Is the Difference Between a C3 and a C4 Plant?

C3 plants use C3 photosynthesis which uses CO2 in a 3-carbon compound and C4 plants use C4 photosynthesis which incorporates the CO2 in a 4-carbon compound. These compounds represent different types of sugar.

Photosynthesis is the process of combining light and nutrients of the soil to create energy plants can use. C3 and C4 photosynthesis go about this process differently. Most plants are C3 types. The advantage with C3 photosynthesis is that it is more efficient than the C4 variety under normal light conditions since it requires fewer enzymes. C3 plants use C2, or Carbon.

Dioxide is used to create the 3-carbon compound G3P in order to produce usable energy. The higher CO2 concentration in C4 plants means that the stomata, the gas exchange part of the plant, do not need to open up to get any more, so less water is lost. C4 uses CO2 to create the 4-carbon compound oxaloacetate instead. C4 plants tend to do better in high oxygen environments. C4 plants also go through photosynthesis faster than C3 plants when there is a lot of light and heat nearby. Additionally, C4 plants have much better water efficiency than the C3 variety since they don’t have to keep their stomata open as much.

There are several thousand different types of C4 species with 19 different plant families. Examples include corn, saltbush and many plants that thrive during the summer months.