Tuesday, 14 July 2009

Lichen

Something a little different today. Lichens are composite organisms consisting of a symbiotic relationship between a fungus and either an algae or bacteria. Lichens grow in some of the most inhospitable parts of the world and under extreme circumstances. This particular one was growing on our roof until dislodged, possibly by a Magpie. It's called Xanthoria parietina.
One of the so-called 'leafy' lichens, it was used in times gone by as a treatment for jaundice, because of it's colour - without success, it must be said!
The leathery surface of this lichen is formed by fungal hyphae (the 'root-like' structures of a fungus). This skin is essential to limit water loss and so prevent dehydration in the arid conditions of walls, roofs, etc.
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