(Remember: Sat 20 June 2015: date of introductory lichens workshop here)
From where you are standing in front of the cross, turn 90 degrees to the left and look at the outside of the church wall. The wall is made of limestone, except for the capstones, which are made of gritstone. There is a black crustose lichen on the limestone, which,with close inspection, has a blue edge. This is Placynthium nigrum. The thallus is delimited by a wide dark blue felted prothallus, and the inner part of the thallus has a scaly texture
The moss is Wall Screw-moss - Tortula muralis
Nearby on the limestone is a yellow powdery looking lichen
Caloplacca citrina |
If you look closely there are some jam tart shaped tiny cups with white rims and golden yellow centres. These are the reproductive bodies called apothecia. This is Caloplaca citrina which grows on hard limestone. If a drop of alkali is added (KOH) it should go crimson.
Walk 2 m along the churchyard wall on the left, so that you are looking at the wall but with the cross nearby
The capstones are made of sandstone/gritstone |
On top of the gritstone capstone there are patches of a very white crustose lichen.
This has been grazed by slugs and much of it removed so it is not possible to say what speicies it is. |
If it is dry, the black lichen is pressed against the wall, almost as thin as paper. It grows in cracks in the limestone wall and on the mortar. When wet it is greenish black, as below.
Here it is closer up. The tiny spherical blobs are called idisia. They can break off and get carried away and then grow and form new plants.
Near by, and lower down is another species of black jelly lichen - It is Leptogium lichenoides. Its lobes are rather thin, concave, with deeply incised margins so it looks frilly. It dries brown/lead grey, not blackish as do the Collemas.
Leptogium lichenoides
Leptogium lichenoides
|
Near by - Is this another black jelly lichen? It certainly feels like jelly.. or more like goo.
Or is it just a blue-green alga?
Or is it just a blue-green alga?
Agonimia tristicula - a tiny tiny lichen hidden in the dark crevices - near the green signpost |
Agonimia tristicula |
Agonimia tristicula |
A 2cm diameter yellow dry patch nearby, when examined closely, has more structure
On the hard limestone rock you can see white lichens and there are tiny holes, some empty, some filled with black material - At first I though it was Verrucaria baldensis (if the perithecia (black dots) are .25mm diameter).
But very close inspection show the black fruiting bodies have greyish rims -so they are apothecia
rather than perithecia - bun shaped, with a star shaped hole on top.
So it must be Clauzadea immersa
See the pale grey rims round the black apothecia of Clauzadea immersa |
End of Site 2.
Click to go to Site 3
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THE SEVEN POSTS IN THIS SERIES
2. The lichens on the wall in the foreground to the left of this picture
3. The lichens on several graves near to this one:-
4. The lichens on the flat slab of this table tomb
5. The white lichens round the door to the church
6. The lichens on the branches of the tree
7. The lichens round the back of the church
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