Question

What are the different types of lichen based on their external forms?

Answer 1

Based on the external form, the lichens are of five types:

1. Leprose- In this type the fungal mycelium envelops the algal cells. It appears as powdery mass. For example Lepraria incana.
2. Crustose- This lichen appears as a thin layer or crust and is wholly or partially embedded within the substratum. For example Rhizocarpon.
3. Foliose- This lichen is leaf-like in appearance and shows lobes in the thallus. It is attached with the substratum by the help of rhizines. For example Parmelia.
4. Fruticose- This lichen appears like a shrub and has a well-developed thallus. For example, Usnea.
5. Filamentous- In this lichen algal partner is filamentous and fungal partner shows few hyphae. For example, Racodium.