Lichens: An Overview

Lichens are unique organisms that arise from a mutualistic relationship between a fungus and an alga or a cyanobacterium. The fungus provides structural support and protection, while the alga or cyanobacterium provides nutrients through photosynthesis. This partnership allows lichens to thrive in a wide range of environments, from arctic tundra to deserts.

Structure of Lichens

Lichens have a characteristic structure consisting of a thallus, which is the main body of the lichen, and often a fungal mycelium that provides support. The thallus can take on various forms, including crustose (crusty), foliose (leafy), and fruticose (shrubby).

Ecological Importance

Lichens play a crucial role in their ecosystems. They contribute to soil formation, serve as a food source for various organisms, and can indicate air quality. Some lichens are also used in traditional medicine and dyes.

Study Guide

1. What is a lichen?
2. Describe the mutualistic relationship between the fungus and the alga or cyanobacterium in lichens.
3. Explain the structure of lichens, including the thallus and fungal mycelium.
4. Discuss the ecological importance of lichens and their role in ecosystems.
5. Give examples of different forms of lichens and their adaptations to different environments.