Due to their adaptability, plants live in almost every conceivable environment on the earth. Many times, plants have evolved to live in situations where little moisture is present in the environment. These plants' structures can receive the maximum amount of food with the lowest rate of evaporation of water. Conserving water as a valuable resource saves plants and allows them to cling to existence in harsh environments.
Adaptations that cause leaves to roll into circles reduce the amount of water lost to the sun while trapping cool air in the central part of the leaf. Further, evaporation is lessened by reducing the surface area exposed to wind evaporation.
Thick Waxy Cuticle
The cuticle of a leaf cuts down on water loss by acting as both a barrier to evaporation and by reflecting light away from the leaf, reducing its amount of collected heat. This adaptation is common among evergreen plants.
Needle-shaped and other small leaves reduce the total surface area of the leaf, causing less evaporation of water due to a combination of less heat being absorbed by individual leaves and by the sun having a smaller surface area over which it can evaporate water.
Some plants, like living stones, expose only a very low number of leaves to the sun, leaving the rest of the plant beneath the surface of the earth, away from the heat that may cause further water loss.
Plants such as the desert lily may go dormant during dry periods. During this dormancy, bulbs and other reproductive units may stay in the ground and will not activate for growth until conditions change enough to support their growth (usually meaning an increase of moisture in the plant's environment).
Some plants, such as the barrel and organ-pipe cacti, can store large amounts of water in their thick stems beneath a pulpy exterior. They can draw on this water during drier times to keep alive in hars, desert environments. The thick exterior prevents evaporation and allows the plant to effectively utilize the little moisture that it comes in contact with.