I am not particularly interested in Lichens but they seem to command my attention now a days and for what reason I cannot fathom. Maybe it is because they are so prolific where I live. Almost everywhere one looks there are lichens in great abundance, the trees in the forests are nearly covered in them. Also I have found myself to have started a rather small collection of the little crispy looking critters.
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.
Lichens, Interesting or Not...?
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Yes I also should have mentioned that my recent unsought obsession has prompted me to to some research into the prolific little organisms. I have found that I am most interested in the biomonitoring techniques used in Lichenology and the techniques used for dating objects in areas where lichens are in abundance.
I have found out that grave yards or cemetaries are good places to begin a study of lichen growth, since the grave stones have dates on them as to when they were erected or close to when they were placed and the lichens that may be found growing on them have varying rates of growth per year. Considering the growth rate of a particular lichen, one can closely assess the approximate age of the substrate on which a particular lichen was found. Some lichens grow only 0.5mm/year and some attain rates of 5mm/year and again some may attain a growth rate of 9 cm/year but those high growth rates are rare. From the size and number of lichens around my home, they seem to grow pretty fast. Thanks Rik.
I have found out that grave yards or cemetaries are good places to begin a study of lichen growth, since the grave stones have dates on them as to when they were erected or close to when they were placed and the lichens that may be found growing on them have varying rates of growth per year. Considering the growth rate of a particular lichen, one can closely assess the approximate age of the substrate on which a particular lichen was found. Some lichens grow only 0.5mm/year and some attain rates of 5mm/year and again some may attain a growth rate of 9 cm/year but those high growth rates are rare. From the size and number of lichens around my home, they seem to grow pretty fast. Thanks Rik.
Indeed they are an indicator species Doug. It is a wonder however, that something that seems so unimportant as a lichen can mean so much. Just to look at them one would not give them a second thought but to assume that what ever they are growing on must be very old. Which indeed there too would be a correct assumption. Just think if I lived in the Northwest, maybe I could try and put a date on a glacier by using lichenometry Thanks Doug.