Leaves take in carbon dioxide (CO2) through their pores, which are called stomata.

Here's a breakdown:

* Stomata: Tiny openings on the surface of leaves, usually on the underside.

* CO2: A gas essential for photosynthesis, the process plants use to make food.

So, the leaves use their pores to absorb CO2 from the air, which is then used in photosynthesis.