The cuticle is a thin, waxy, water-resistant layer that covers the outer surface of leaves, stems, flowers, and other aerial plant parts. It is composed primarily of cutin, a polymer of fatty acids, along with embedded and surface waxes. The cuticle forms the boundary between the plant and the surrounding environment.
Its primary functions are to reduce water loss, protect against pathogens, shield tissues from ultraviolet radiation, and help regulate the movement of water and gases across the plant surface. Cuticle thickness and composition vary widely between species and are influenced by factors such as light intensity, humidity, temperature, and plant age.
A well-developed cuticle is an important component of a plant’s physical defense system. It can slow the penetration of pests, fungi, bacteria, and chemicals, while helping maintain leaf hydration during periods of environmental stress. Damage to the cuticle, whether from abrasion, solvents, excessive heat, or certain pesticides, can increase water loss and make tissues more vulnerable to injury.
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