Wrinkles on Sepals： Cuticular Ridges Form when Cuticle Production Outpaces Epidermal Cell Expansion

The cuticle is a waterproof coat that covers the outer surface of plant organs exposed above the ground, such as leaves, stems, floral organs, and fruits （but not bark） （Yeats and Rose, 2013）. It prevents the escape of water vapor and can protect the plant from pathogen attack and UV-B exposure. The cuticle is made from cutin, a complex polyester embedded with hydrophobic waxes, and covers the outer cell wall of the epidermis.