Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The cortex is the outermost layer of a lichen's thallus, providing protection and structural support. It is typically composed of tightly packed fungal hyphae.
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The cortex serves as a protective barrier against environmental stress such as desiccation and UV radiation.
It is primarily made up of fungal cells, which are often pigmented to protect against sunlight.
The cortex can vary in thickness depending on the species of lichen and its environment.
Underneath the cortex lies the algal layer, where photosynthesis occurs.
The integrity and composition of the cortex are crucial for the overall health and functionality of the lichen.