Phellem, also known as cork tissue, is a protective outer layer found in the bark of woody plants. It acts as a natural shield, shielding the tree's inner tissues from mechanical damage, extreme temperatures, and pathogens. Resilient and durable, phellem is composed of tightly packed cells containing suberin, a waxy substance that makes it impermeable to water and gases. This layer, symbolized by 🌳🧱, serves as nature's fortress, fortifying trees against the challenges of their environment.