Donnerstag, 31. Januar 2013

Species of the Day - Evernia prunastri (L.) Ach.

After a longer break, which I use to give the article about the very interesting genus of Cladonia a little bit more attention, it's now time for a new article. However, this will also be about a lichen, because it's still winter and this means lichen time. This new lichen is Evernia prunastri (L.) Ach. from the Parmeliaceae family. In German, this species is known as “Flaumenflechte” or “Eichenmoos”. In English, the species' name is “Oakmoss “, what is the literally translation of the German name “Eichenmoos”.

E. prunastri - on a tree

Typical for this species is the bushy and foliose Thallus, which can reach a length between 3 and 4 centimeters. The primary Thallus grows in a small rosette, from which several branches are emanating (this is the secondary Thallus). 

 E. prunastri  - this is a younger individual. The Soralia 
aren't strongly branced yet  

These branches are so called Soralia (similar to C. fimbriata in my previous post); vegetative shoots, which grow through holes on the rough surface of the primary Thallus. These Soralia are repeatedly branched dichotomously and resemble to an antler, what gives the lichen a very special habitus. The number of branches may vary from only a few to numerous. In the last case, the Sorals may form a dense web.

E. prunastri - closer look at the thallus; you can also
see the dichotomy of the soralia

The color of both Thalli varies from a grey green to a pale or yellowish green. Sometimes, a grey color is also possible.

Apothecia are rare at E. prunastri, because the major part of propagation happens vegetative over Soredia. These are small clusters of hyphae and algae, which are located on the ridge or at the margin of the Sorals and be delivered from here. They are normally brighter than the rest of the Thallus but can also have the same color, which makes it very difficult to see them with eye
If Apothecia are present, they are cup-shaped and can be found at the margin of the Thallus. Their inner surface has a dark-brown to rusty red color, while the outer surface has the same color as the rest of the Thallus.

 E. prunastri - on a tree with many other lichens like
Flavoparmelia caperata

E. prunastri is widespread circumpolar in the temperate regions of the Northern and Southern hemisphere. However, some populations have also be found in North Africa. It prefers a neutral to slightly acid substrate and is an epiphyte, which grows on trees. So, it can be found mainly on the barks of broadleaved trees like the oak (Quercus robur, what is also the reason for the name “Oakmoss”). But E. prunastri can also grow on other broadleaved trees (like beech) and even on the bark of some conifers like pines.

E. prunastri - this is an older individual. The soralia are
much longer and more highly branched

This lichen is more common in the lowlands but can also be found in mountainous regions until 1750 meters. It favors a moist and clean air. In dryer regions, the generative propagation through Apothecia and spores is more frequently. This suggest, that the Soralia grow better in a more humid air.

Due the high amount of fragrances, E. prunastri has become a Basenote in the perfume production. The distilled fragrance is known as “mouse de chenne”. However, these ingredients can also cause an allergic reaction to the skin, and therefore the use isn't so common today.

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