In heteromerous thallus, algae and fungal components are arranged in four definite layers.
Upper cortex, algal layer, medulla and the lower cortex. eg: Parmelia
1.Upper cortex: made up of compactly arranged, thick walled fungal hyphae without intercellular spaces
2. Algal zone: Photosynthetic region with algal cells intermingled with fungal hyphae
3. Medulla: consist of thick walled, loosely arranged hyphae with large intercellular spaces
4. Lower cortex: made up of compactly arranged, dark coloured, thick walled fungal hyphae without intercellular spaces or spaces filled with gelatinous material.
Numerous hyphal projections arising from the lower side are called as rhizines, which helps in attachment to the substratum
Upper cortex, algal layer, medulla and the lower cortex. eg: Parmelia
1.Upper cortex: made up of compactly arranged, thick walled fungal hyphae without intercellular spaces
2. Algal zone: Photosynthetic region with algal cells intermingled with fungal hyphae
3. Medulla: consist of thick walled, loosely arranged hyphae with large intercellular spaces
4. Lower cortex: made up of compactly arranged, dark coloured, thick walled fungal hyphae without intercellular spaces or spaces filled with gelatinous material.
Numerous hyphal projections arising from the lower side are called as rhizines, which helps in attachment to the substratum
