Anatomy

Typical foliose and fruticose lichens have a layered internal structure:

Upper Cortex

• Protective skin of densely packed fungal cells
• Provides UV protection and water regulation

Photobiont Layer

• Green algae or cyanobacteria cells
• Carries out photosynthesis
• Often visible as a greenish or bluish layer when broken

Medulla

• Loose network of fungal hyphae
• Stores water and nutrients, facilitates gas exchange

Lower Cortex (sometimes absent)

• Protective underside, often with darker pigmentation
• May include rhizines

Rhizines

• Root-like fungal attachments (not true roots)
• Anchor the lichen to bark, rock, or wood

Apothecia / Pycnidia

• Reproductive structures on upper surfaces or margins