Antitranspirant A chemical that reduces transpiration. Antitranspirants may work by depositing a waterproof film over the stomata or by inducing stomatal closure.
So the carbon dioxide comes in through the stomata, makes it's way through gaps in the airy layer of cells (called spongy mesophyll) at the bottom part of the leaf, then heads up to the palisade layer for photosynthesis.
And one of the most important things that mosses contributed to the development of land plants is the stomata — those mouth-like pores that allow gases to move in and out of the plant.
Signals about their stressed state can pass to any neighboring plants that touch roots, so those plants know to prepare for drought by closing their stomata, too.