Narrative

Lichens (Phylum Lichenes) are an unusual type of life form in that Lichens are actually composed of two different kinds of life. Lichens are composed of algae and fungal threads working together to create an unusual group of life forms. Because of this combination of life forms, Lichens can be placed in a variety of places in the taxonomy tree. Any choice of taxonomic placement is open to dispute. Lichens can survive in a variety of harsh habitats. In fact, they are relatively more common in rather cold habitats. Lichens (Class Lichenes) are composite organisms that thrive under extreme climatic conditions, and, therefore, have an ability to grow where few other plants can survive, i.e., rocks, deserts, and extreme northern areas. They consist of a unique intergrowth of a fungus with a single- celled green algae. They are often brightly colored, as is the genus Claydonia (pictured). Many of them are intolerant of pollutants in the atmosphere. Their presence or absence indicates the degree of purity in the air. The Scots use lichens as the dye base for their Harris tweeds. Some are used as smoking products, some as medicines. Reindeer and Caribou depend to a large extent on these plants for food. A few species are poisonous.

Because lichens appear to be a combination of both an algae and a fungal type of growth, some taxonomists place them higher in the evolutionary scale than the fungi.

Taxonomy

References