Talk about cuticle

Those in aerial part of the plant secrete a waxy, water resistant layer, cuticle on their surface, composed of fatty material (cutin) and waxes. Cuticle thickness varies depending on age and species of plant. very thin and absent in plants living in humid environments but very thick in plants in dry environments , the cuticle with the outer wall helps in protection against water loss, mechanical injury and invasion by fungi and bacteria