Why are C4 plants well adapted to hot and dry environments?

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Diagram of a tree leaf illustrating photosynthesis, with arrows showing sunlight, water, and carbon dioxide entering the leaf and sugars and oxygen being produced. A person is shown beside the tree to demonstrate the exchange of oxygen and carbon dioxide between plants and animals. — Photosynthesis Diagram of photosynthesis showing how water, light, and carbon dioxide are absorbed by a plant to produce oxygen, sugars, and more carbon dioxide.

C4 plants are highly adapted to hot and dry environments because they have evolved a specialized mechanism to minimize photorespiration and conserve water.1

In these conditions, plants often partially close their stomata to prevent water loss, which reduces internal carbon dioxide levels. While standard C3 plants rely on the enzyme Rubisco—which can mistakenly bind oxygen when CO2 is low—C4 plants utilize the enzyme phosphoenolpyruvate (PEP) carboxylase.1

PEP carboxylase has a much higher affinity for CO2 and does not react with oxygen, allowing these plants to fix carbon efficiently even when stomata are restricted. By spatially separating carbon fixation between mesophyll and bundle-sheath cells, C4 plants concentrate CO2 around the photosynthetic machinery. This process effectively suppresses photorespiration, allowing species like sugarcane and corn to maintain high rates of photosynthesis while losing significantly less water than C3 plants.1