Flexi Says: The waxy leaf coating (cuticle) limits water loss, but in doing so also limits the absorption of carbon dioxide (CO2) and release of oxygen (O2). These functions are served by stomata which open and close to regulate gas exchange. In most leaves, stomata are more abundant in the lower epidermis, limiting water loss due to direct sunlight. However, the amount of stomata in leaves can vary due to a plant's environmental conditions, including amount of sunlight, temperature, humidity, and carbon dioxide levels in the air.
