Lichens: Explanation and Study Guide

What are Lichens?

Lichens are unique organisms that arise from a symbiotic relationship between a fungus and an alga or cyanobacterium. The fungus provides a structure and protection, while the alga or cyanobacterium provides nutrients through photosynthesis. Lichens are commonly found on rocks, trees, and other surfaces, and they come in a variety of shapes and colors.

Types of Lichens

There are three main growth forms of lichens: crustose (crusty), foliose (leafy), and fruticose (shrubby). Crustose lichens are tightly attached to the substrate, foliose lichens have a leafy appearance, and fruticose lichens are bushy or shrubby in appearance.

Ecological Importance

Lichens play a crucial role in the environment as they can colonize harsh habitats and help to break down rocks and organic matter. They also serve as a source of food for animals such as reindeer and caribou, and some lichens have medicinal properties.

Study Guide

1. What is the symbiotic relationship involved in the formation of lichens?
2. List and describe the three main growth forms of lichens.
3. Explain the ecological importance of lichens.
4. Identify and describe the different components of a lichen (fungus, alga/cyanobacterium).
5. Discuss the role of lichens as indicators of air quality.