Sunday, 29 January 2012

Lichens

A wander around the garden this weekend revealed the exquisite beauty and detail of the lichens growing on the trees. 
Lichens are 'dual organisms'. Every lichen is a partnership between members of two different kingdoms which live together in a special, mutually beneficial relationship - a symbiosis. Each lichen is made up of a fungus and an algae.
The body of the lichen is built up by tough fungal hyphae, and the algae live inside that framework.
The fungus protects the algae from the harsh world outside, and provides it with water and mineral nutrients. The algae makes its own food by photosynthesis, and leaks some of this food, which is then absorbed by the fungus, which cannot make its own food.
The partnership is so tough and self-reliant that lichens can grow in places like bare rock in deserts, where nothing else can survive. When it is too dry, too hot, or too cold, lichens go into a state of suspended animation until conditions improve.
Since the algae make up only about 5% of each lichen, and are out of action for much of the time, you can imagine that lichens grow very slowly - only a few millimetres per year. They make up for this by living for centuries, or in a few cases, millennia.
Lichens have only one serious weakness - they must absorb their mineral nutrients from the rain. So if the air is polluted with sulphur dioxide, this dissolves in the rain and is absorbed by the lichens which often die as a result.

20 comments:

  1. Hello Rosemary,
    their pictures reveal exquisite details!
    Looking for artist!
    a hug

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    1. Dear Antonio - you are right their lovely detail does require an artist to paint them, could you be just that person?

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  2. Rosemary, I did not know this and they have their own curious beauty I think. Olive

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    1. Dear Olive - I agree they do have a curious beauty, and also a curious lifecycle.

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  3. Dear Rosemary, what an interesting post and the photographs are superb.

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    1. Dear Gina - thank you for your kind comments re: the photographs. Sometimes images turn out better than you hoped and sometimes the opposite happens. I am pleased you found it of interest.

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  4. Some great shots. Love your focus in these pictures. Beautiful photo work.

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    1. Dear Fotokarusellen - thank you for your very kind comments, coming from such a wonderful photographer as yourself that is high praise indeed.

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  5. Hello Rosemary:
    Well, although in our gardening days we were only too aware of the lichens on trees, shrubs, stones and wood all around the garden, we had never really thought about their lifecycles. Thank you for such an informative post and for the wonderful close-up views of the many marvellous lichens round your garden.

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    1. Dear Jane & Lance - it is surprising how often we see and yet we do not see. It wasn't until I started focusing the camera on the lichens that I realised how beautiful they were. The relationship between the fungus and the algae is quite extraordinary.

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  6. A very interesting and informative post! The images are absolutely fantastic! So much beauty in nature!

    Ciao!

    ANNA

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    1. Dear Anna - pleased that you enjoyed reading about the lichens. They are so small that we sometimes miss seeing the beauty in their structure.
      Ciao!

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  7. spectacular and other worldly!

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    1. Dear Rachel - thanks for visiting, you are right they are other worldly, but totally fascinating too.

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  8. Very interesting about the lichens.. I have some here and there on my olive trees.. but very little
    I now know how they survive.
    Your photos of the different types are beautiful..
    thank you Rosemary, i will certainly look at them now in a different way.
    val

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    1. Dear Val - I wonder if your lichens are a different type to mine? They do have an interesting lifecycle and amazing that they can live for thousands of years.

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  9. Hello, Rosemary - I never knew that about lichens! I must say that the ones in your garden are as attractive as they are curious. And your weather conditions must be perfect for all this growth. Now I'm wondering, do the lichens harm the tree at all?

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    1. Hello Mark - No, they do not harm the trees. They just use the bark as a medium, just as it does on rocks, or old buildings. Lichens may rest directly on the bark or be attached shallowly to it, but they do not enter the inner bark where food is transported, and hence do not rob the tree of nourishment. They are not parasites.

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  10. Incredibly fascinating Rosemary! I see lichen about the place, but had no idea of this fungus symbiosis business. The air in your area must be jolly clean to have such an array of this stuff around!

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    1. The symbiosis between the fungus and the algae is an interesting fact about the lichens. Perhaps the air here is good because we live high up, we are 700ft above sea level.

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