Plant Adaptations to Water

Structural adaptations- leaf shapes, size and form

Water makes it possible for a tree to transport nutrients from the soil to the leaves, and is the medium through which it exchanges gasses with the atmosphere across the leaf surface. Foresters generally regard trees as drought tolerant or intolerant.

The hard, waxy coating on the leaves of drought tolerant trees is an adaptation for conserving water. For example, the hard covering of a pine needle prevents water from evaporating through the surface of the leaf, making it generally more water-use efficient than broad-leaved trees. Pines also have sunken stomata, which means the openings in the leaf are not directly exposed to wind. These adaptations allow pine needles to get CO2 from the atmosphere without losing too much water during the process of photosynthesis.

Some broad-leaved trees have evolved hard, waxy coverings, such as live oak and post oak. Still other trees such as the southern red oak have evolved a hairy undersurface, which slows the evaporation of water from the stomata.

A leaf that is not transpiring water is in danger of overheating under full-sun conditions. The small size and narrow shape of pine needles allow maximum exchange of heat with the surrounding air. Some broad-leaved trees, such as scarlet oak and southern red oak, have deeply lobed-leaves, which similarly acts to maximize heat exchange.

Note: the following list is incomplete.