Lichens of the Weston Ranch
Lichens are composite organisms, each consisting of a fungus species that has succeeded in establishing an ongoing parasitic relationship with a green alga or cyanobacteria. The fungus is dominant and the name of a lichen is really the name of its fungal component. -Karl Anderson
Lichens are unusual because each is actually made up of two distinct types of organisms. This composite is made up of a fungus and another organism that can carry on photosynthesis. The photosynthetic partner is a green alga or a cyanobacterium (a blue-green alga). What is even more unusual is that the lichen does not look like either of its two constituent organisms if they were living separately.
Lichens can be found on trees and shrubs, rocks, and soil. They do not harm the plant they are growing on. Lichens can also be found on objects made by humans, such as old sidewalks and stone monuments in parks and cemeteries. Lichens have sometimes been called “nature’s pioneers” because they are often the first to colonize newly exposed land surfaces. Lichens can break down rock surfaces although this is a very slow process.
Lichens are not able to grow well where air pollution occurs. Their presence or absence has been used as an indicator of the long-term quality of the air in cities.
The lichens for this study were collected on the Weston Ranch from 2007 to 2009 as part of a larger study of the vegetation of the ranch. Lichens were collected and brought to the laboratory for study and photography under a stereomicroscope. -Alan Lievens and Mark Gustafson and Shirley C. Tucker
For more information about lichens, check out Lichens of the Weston Ranch by Alan Lievens, Mark Gustafson, and Shirley C. Tucker.