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Pollution indicator
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| [Note Guidelines] Photographer's Note |
On my yesterdays hike through the forest I was not able to capture some birds or wildlife,however I was able to capture some pictures of some lichen,wherof this is one of them.
Usnea
Usnea is the generic and scientific name for several species of lichen in the family Parmeliaceae, that generally grow hanging from tree branches, resembling grey or greenish hair. It is sometimes referred to commonly as Old Man's Beard, Beard Lichen, or Treemoss. Usnea looks very similar to Spanish moss, so much so that the latter plant's Latin name is derived from it (Tillandsia usneoides, the 'Usnea-like Tillandsia').
Usnea grows all over the world. Like other lichens it is a symbiosis of a fungus and an alga. The fungus belongs to the division Ascomycota, while the alga is a member of the division Chlorophyta.
Many species have been described. A monography by Józef Motyka from 1947 distinguished 451 species. Many of these are now regarded as morphological varieties and adaptations to local circumstances. The taxonomic categorization of many members of this genus remains uncertain. The number of recognized species in Finland is decreasing for this reason, from 34 in 1951 to 25 in 1963 and only 12 in 2000. It is now noted as including more than 600 species and being one of the largest genera within the Parmeliaceae.(Ref. Wirtz, N. et al 2006.)
Usnea is very sensitive to air pollution, especially sulfur dioxide. Under bad conditions they may grow no larger than a few millimetres, if they survive at all. Where the air is unpolluted, they can grow to 10-20 cm long.
Usnea has been used medicinally for at least 1000 years. Usnic acid (C18H16O7), a potent antibiotic and antifungal agent is found in most species. This, combined with the hairlike structure of the lichen, means that Usnea lent itself well to treating surface wounds when sterile gauze and modern antibiotics were unavailable. It is also edible and high in vitamin C.
This lichen, promoted to induce weight loss via increase in metabolic rate, has been the topic of an FDA warning in the USA, due to hepatotoxicity in a product called Lipokinetix. Lipokinetix also contained PPA, caffeine, yohimbine and diiodothyronine. There is no scientific information on the safety or efficacy of oral use of Usnea. |
Jamesp, Argus, kebapci, JORAPAVI, uleko has marked this note useful
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- Jamesp
![Gold Star Critiquer/Gold Note Writer [C: 1252 W: 0 N: 4842]](http://i1.treknature.com/misc/g-n-g.gif)
(14380) - [2008-02-11 1:28]
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Hi Paul
Good capture of this lichen or rather lichens. The exposure and detail are both good.
It is possible to use lichens to date objects - for instance - drystone walls - if you know the growth rate of the lichen and find some growing over two stones, you can calculate how old the wall is (or at least - roughly how long since they were last moved).
James
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- Argus
![Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 2611 W: 133 N: 7494]](http://i1.treknature.com/misc/g-g-g.gif)
(23373) - [2008-02-11 1:39]
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Hello Paul,
Excellent lichen shot, the Usnea trailing nicely and quite long from the old dead tree, which suggests that the air where you took this shot is relatively clean. Here in Scania we get pollution from Poland and Copenhagen and it is rare to find such long lichens.
Thanks for sharing this interesting image,
Ivan
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- albert
(717)
- [2008-02-11 1:52]
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Hi Paul
Good photo and interesting comments
Best regards
Albert
Good to see there are portions developed countries in which 'long hairs' grow. Thank for the info BTW.
Hola Paul,
No es nada fácil hacer una buena foto de líquenes, en esta has conseguido un buen trabajo con detalle y una buena nota informativa. Saludos
José Ramón
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- uleko
(23564)
- [2008-02-11 9:32]
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Hello Paul,
Snap, we've both got Usnea today! :-) This is a fine long specimen that you've captured really sharply. Good light and colours and a fine composition too.
TFS and cheers, Ulla
