Why are the stomata in most plants more numerous on the lower surface of a leaf instead of being on the upper surface?
The function of stomata is exchange of gases and release of water in the form of water vapour. In a dicot leaf, which is dorsiventrally distinct. The adaxial or dorsal side is exposed to light and has compactly arranged palisade tissue which primarily performs photosynthesis. The spongy mesophyll having numerous air gaps is forms the ventral or abaxial surface of the leaf this facilitates movement of water vapour towards the exterior and hence more number of stomata are present on the lower or abaxial surface of the leaf.