Lichens
Lichens are composed of multiple living organisms making them a symbiosis. Symbiosis means that two or more organisms live together and have a more successful partnership than they would living on their own. Lichens are composed of a fungus and one or more algae. This companionship works because the fungus gets nutrients, like sugar, from algae, and the algae gets protection from the fungus. Lichens can only reproduce asexually. There are small cracks on the upper cortex which release soredia, small pieces of lichen containing fungal hyphae and algal cells, and if blown or washed to a favorable site they will reproduce. They can also break apart rock which is an important process for soil genesis. There are three types of Lichens: Crustose, Foliose, and Fruticose.
Crustose Lichens
consist of an upper cortex, algal layer, and medulla. They form crusts that are tightly attached to their surfaces making it nearly impossible to remove them from the surface they are on. |
Foliose Lichens
consist of an upper cortex, algal layer, medulla, lower cortex., and rhizines. These lichens are leaf-like and made of lobes. They are loosely attached to their surfaces because of the hairlike rhizines which makes them easy to remove. |
Fruticose Lichens
consist of an upper cortex, algal layer, medulla, and inner layer. These are very 3-D., round and centrally arranged, and mostly branched. They can grow upward like shrubs or down in long strands. |
References
"Lichen Vocabulary." Lichen Vocabulary. Web. 3 Dec. 2014. <http://www.lichen.com/vocabulary.html>.
"Loveable Lichens." The Earth Life Web, All About Lichens. Web. 3 Dec. 2014. <http://www.earthlife.net/lichens/intro.html>.
"Lichen Vocabulary." Lichen Vocabulary. Web. 3 Dec. 2014. <http://www.lichen.com/vocabulary.html>.
"Loveable Lichens." The Earth Life Web, All About Lichens. Web. 3 Dec. 2014. <http://www.earthlife.net/lichens/intro.html>.