Ramalina fraxinea
From Wikipedia, the free encyclopedia
| Ramalina fraxinea | |
|---|---|
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| Ramalina fraxinea growing in Eglinton Country Park, Scotland. Note the stalked apothecia. | |
Scientific classification  | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Lecanoromycetes |
| Order: | Lecanorales |
| Family: | Ramalinaceae |
| Genus: | Ramalina |
| Species: | R. fraxinea |
| Binomial name | |
| Ramalina fraxinea | |
| Synonyms | |
Ramalina fraxinea, the cartilage lichen,[1] is a fruticose lichen with erect or pendulous thalli and branches that are flattened. Colour varies from pale green though yellow-grey to white-grey; apothecia are frequent and soralia may also be present.
This lichen is widespread in the United Kingdom, being found on tree bark. In north-eastern England and eastern Scotland it is often well developed, growing up to 12 cm with thongs of up to 2 cm wide. In less favourable areas it is much smaller.[2] The species has declined markedly since the mid 20th century and is now rare or absent in many UK areas.[3] Its sensitivity to air pollution and fertilizer enrichment may be reasons for the decline.[4] It is mainly found on the bark of Acer, Fraxinus, Populus, Tilia and Ulmus; it has been found growing on Rhododendron[5] and oak.[6]
It has been recorded in Netherlands,[7] Spain,[8] Belgium, Luxembourg, France,[9][10] England, Scotland,[10] Hungary,[11] Norway[12] and Latvia.[13] The species has been widely recorded in the United States of America.[14]
Ramalina fraxinea likes windy, exposed and well-lit sites and it is found on species with nutrient-rich bark.[15] The species also likes humid or foggy areas near ponds or rivers.[16]
Structure and appearance
The Latin word ramas means 'branch'. This genus is a shrubby or fruticose group with erect or pendulous thalli. The branches are flattened and rather stiff. Colour varies from pale green though yellow-grey to white-grey. Apothecia are frequent and soralia may be present. Apothecia are usually concave and often pruinose.
The branches of R. fraxinea have a very distinctive shape, being widest toward the middle (as much as 4.5 cm in some specimens) and tapering at both the point of attachment and toward the tip (to about 1 cm). The thallus is green-grey in colour, pendent and may be as long as 10 cm. It has the overall appearance of being coarsely tufted, individual branches showing a channelled, wrinkled appearance. The branches may have a twist or turn to them. The apothecia are cup-like and convex and are found both along the edges of the branches and on the surface or lamina.[17]
The Ramalinas are also known as 'bush', 'strap',[16] or 'gristle' lichens.[5] They always grow upside-down, and this plant looks like seaweed nailed to a tree.[18]
Life cycle
The spores are kidney-shaped. It does not contain as many apothecia as Ramalina fastigiata.[17] The specimens in the photographs here shown here are very large, but does not have many apothecia, the spore-producing discs. The few that were present were borne on short stalks, and were located on the surface of the lobes, especially near the edges.[15] Ramalina fraxinea is a polycarpic species, so sexual reproduction does not cause the death of the thallus; once apothecia have developed, it can continue producing sexual propagules throughout its lifespan.[19]
Sensitivity to air pollution
Ramalina fraxinae is very sensitive to air pollution (SO2). It likes windy, exposed and well-lit sites and is found mainly on trees.[17] It was found in Edinburgh in 2008 after an absence since 1797 due to air pollution.[5]
