Most leaves of terrestrial plants have more stomata in the lower epidermis and less stomata in the upper epidermis. The stomata of floating plants are generally distributed in the upper epidermis of leaves, and the number of stomata in the lower epidermis is very small, even ; For plants with upright leaves, there are as many stomata on both sides of the leaves.

this is a phenomenon that plants adapt to the outside world, that is, they can exchange gas with the outside world and avoid excessive evaporation of water in the body to a certain extent.