Structural Features of Leaf

Certain plants are adapted to reduce the rate of transpiration, eg., by reducing leaf size, the transpiration

surface is reduced. Some xerophytic plants have needle-like leaves to reduce transpiration. The presence

of thick deposition of caution or wax-like substances on the leaf surface also reduces transpiration.

The presence of sunken stomata (as in Calotropis, Nerium, and Cycas) helps in reducing stomatal

transpiration. These sunken stomata are found in cavities surrounded by hairs. These depressions accumulate

more water vapor reducing the diffusion rate of water through this pore. (Fig.7).

The presence of hydrophilic compounds such as gums, mucilage, etc. helps in retarding the rate of

transpiration. Several factors such as leaf area, amount of spongy tissue, the volume of intercellular spaces,

the orientation of leaf, and extent of root system also affect transpiration rate.