Mittwoch, 6. Februar 2013

Species of the Day - Flavoparmelia caperata (L.) Hale

The Lichen-Weeks continue with another species: Flavoparmelia caperata (L.) Hale from the Parmeliaceae family. In English, this lichen is known as “greenshild” lichen” due its habitus and color. In German, it's known as “Caperatflechte”. This name bases on the Latin word “caperatus”, which means “runzelig (wrinkled)” in German.

F. caperata - on a tree

The foliose thallus of F. caperata grows flat on the substrate and is coarsely and irregularly lobbed. It is very large for a lichen and can reach about 20 centimeters in diameter. When dry, the upper surface has a grey to green color, which is typical for this species and makes it simple to differ it from other species like Parmelia sulcata. If the Thallus is wet, the color changes to a distinctive yellowish green. The surface is smooth but became rough with age. In contrast, the lower side of F. caperata is black


F. caperata - thallus; you can also see some soralia 
(black spots)

Apothecia are rare and spreading mostly happens vegetative per Soralia. Normally, these Soralia are situated in large numbers in the center of the Thallus and look like small, black stains. The Soredia, the primary diaspores, are granular to lentil-shaped.

F. caperata - on a bark; together with Evernia prunastri

When Apothecia are present, they are disc-shaped and have a brown color. They are about 8 millimeters in diameter and sit directly at the Thallus with no stalk (they are sessile).

F. caperata - Thallus with its grey green color;
also on this pictura are soralia (s)

F. caperata is a very common lichen and can be found on many trees in the temperate regions of all continents. It prefers an acidic substrate and grows mostly on the bark of broadleaved trees and shrubs like beeches or oaks. In some rare cases, the species also grows on rocks (mainly silicates).



F. caperta - the black ventral site with its adhesive organs;
please not also the thin, black edge

The lichen is very sensible towards air pollution and cannot grow in areas with a high emission value. Thus, F. caperata was rare in the lowlands but through measures to increase the air quality (like the flue-gas desulfurization) it has become more common again. Because of this, F. caperata is a good indicator for air quality.

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