Cuticular Transpiration

i. Cuticular transpiration: Cuticular transpiration is water loss occurring by simple diffusion straight through the cuticle — a layer of the waxy substance cutin that coats the outer surface of epidermal cells on both leaves and stems. Because it relies on plain diffusion through a waxy layer rather than through any regulated pore, cuticular transpiration proceeds continuously throughout the day and is not switched on or off the way stomatal transpiration is. It typically contributes about 8 to 10% of a plant's total water loss, and its rate is inversely proportional to how thick the cuticle is — a thicker, waxier cuticle (as in many xe …