As you all probably know lichens are actually two organisms that live together in a symbiotic relationship. The fungi, which is actually an Ascomycete which feeds off of anothers work and an algae or sometimes even a cyanobactrium or cyanobacteria. In the relationship the fungi is provided with carbohydrates produced by the algae through photosynthesis and the algae in turn is provided a means by the fungi, to colonize areas that would not normally support algal growth. It has also been suggested by Simon Schwendener, a German, that the relationship between the two organisms is not symbiotic but a form of "controlled parasitism" and that the photobiont cells are actually victims rather than partners in the relationship and that the fungi an Ascomycete, as already stated, surrounds the algae with a fiberous net and entices them to more rapid activity, somewhat like a spider sucking the life from its prey but the fungi leaves the algae very much alive.
Identifying the various species of lichens can be a headache, for me anyway, in that I go by others photographs to identify that which I have found around my home. This is a difficult way to identify them because not all photographs of the same lichen resemble one another, in that the photographs are taken under different lighting conditions and the lichen also may be living or growing under different condtions or different substrates. These are a couple of the species found around where I live. The first one I can only suggest its identification, I cannot be sure. The second is quite common and its features are easily recognized as being a Southern Strap lichen.
Left side image at 10X and the right at 30X Meiji EMZ-13TR with Sony DSC-W5 digital camera attached to the photo tube. ID of this particular lichen is really unknown by me but I will suggest "Flakey freckle pelt" or "Peltigera brittanica." If one looks closely at the right image in the composite, the mycobiont (fungi) and photobiont (algae) can be seen in the center portion of the lichen where it has been torn away.
Left side image at 10X and the right at 25X. The common Southern Strap lichen. These or should I say most lichens if not all, are like little sponges when it comes to pollution. They soak up every bit of it and by chemical analysis one can tell what air pollutants may be in their particular area. The surface of the fruiting bodies as shown in the right side image of the Southern Strap lichen, sometimes are covered with calcium oxylate, which gives them a grayish color. Again I do not know what has compelled me to develop and interest in these things but I always find myself gathering a few to bring inside to study under the scope, expecting to find something.
Thanks Doug.