Types of Lichens
Lichen Growth Forms
In addition, Leprose lichens are powdery masses with little or no organized structure; Squamulose are much the same as crustose, but have raised edges, which can be folded and lobe-like.
All but fruticose lichens grow slowly; their growth, about .5 to 5 mm per year measured by the expansion of their circles. Fruticose lichens, on the other hand grow vertically, and quickly, up to 2 cm per year. Left unchallenged, undisturbed and with a suitably long-lived substrate, it is quite common for a lichen to have a lifespan of several centuries; in fact a certain arctic specimen of a crustose lichen, Rhisocarpon geographicum, was found to be about 9000 years old!
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