Lichen Information Sheet - Some Types of Lichen

About Lichens
Over 500 species of lichens live in the northern forests of North America. Lichens are different from fungi like bread mold and mushrooms--they're farmers.

What's a Lichen? Lichens (pronounced Li'-kens) are a fungus that has captured some algae. These two plants form a symbiotic relationship, that is, each contributes something of value to the other.

Lichen Mechanics: The algae photosynthesizes, making food from the sun's energy. The fungus consumes some of the food produced by the algae and, as its part of the deal, the fungus wraps its fungal threads around the algae, acting as a house for it. The fungus also collects water from rains or moisture in the air and makes this water available to the algae.

Color: Some lichens are green and become brighter green when wet. These lichen fungi have a green-algae partner. Other lichens are not green and don't become bright green when wet. These lichen fungi have a blue-green algae called cyanobacterium as their algal partner. (Some lichens incorporate both green algae and blue-green algae.)

Ecology: Lichens don't have roots so they don't get their nutrients from the soil. Lichens don't usually feed on trees and deadfall like fungi such as puffballs or polypores (shelf or bracket fungi). Lichens absorb water quickly and efficiently from the air, allowing their algal partners to make food from the sun's energy.

Lichens also are a source of food for other creatures such as caribou.

Lichens are very sensitive to air pollution and many die-out when air pollution increases.

Colonizers: Lichens are very good at preparing a disturbed area for more advanced plant species. Raw areas like the barren, rocky land that exists after a glacier retreats or a volcano erupts will often be colonized first by lichen.

Lichen spores called soredia or isidia may be carried considerable distances by birds. Once deposited, the fungal part begins to develop. If it succeeds in capturing wild algae then it may become a lichen.

Lichens in barren areas help create soil by injecting enzymes into cracks in rocks which help break down the rocks into smaller particles. Eventually enough soil may be created to allow colonizing plants to become established from wind-blown or animal-carried seeds.

Science: Scientists have discovered that lichens are some of the earth's oldest living things, sometimes living for hundreds or even thousands of years. Knowing this, they have developed methods to use lichens to help estimate the geologic age of rocks and regions.

Vocabulary
apothecia: saucer-like fruiting bodies often found along edges of leaf or club lichens.
Isidia: tiny wart-like coral-like growths
Medulla: inner "stuffing" of club lichens becomes exposed on the surface as clusters of powdery dust called soredia.
Rhizines: thread or spike type structures from the underneath side of lichens that anchor it to trees, moss, the ground.
Soredia and isidia may be carried to new locations by birds, rain drops, or wind and then start new lichens.