Nature Notes from Argyll
(and occasionally other places)
Sun 18 Nov 2007 Glen Nant
A lichen walk organised by the Forestry Commission and led by lichenologist Andy Acton. This was certainly the most educational guided walk I've been on. We learned a lot about the lichen communities on different types of trees, and I was shown a great many lichens that I'd never noticed before, despite having walked the route at least twice in the past.
I only bothered to photograph species that we haven't had on the site before, and the photos are of no great quality as I took them in a hurry so as not to miss what people were looking at next! Also the weather was dull and showery, the wood was shady and towards the end the daylight started to fade. End of excuses. Now that I know what to look for I'll try and get some better pics of these species in due course.
First we looked at lichens of the Lobarion community, which prefers bark that is not too acid. On a group of willows we found Lobaria pulmonaria, L scrobiculata, L virens, Pseudocyphellaria crocata and Degelia atlantica, all of which have featured on this site before (see species index for links to pics). Also the two above which were new to me: Leptogium burgessii, with its extraordinary frilly edges to the apothecia, and Pseudocyphellaria norvegica, which is similar to P crocata but with white lines and dots instead of yellow.
Previously we've had Sticta sylvatica; here are two new Stictas. The blackish bit on the left of the first pic is Sticta fuliginosa, which like S sylvatica smells of fish. Next to it on the right of the pic, paler, is S sylvatica, but not in very photogenic shape. The other new one, in the 2nd pic, is Sticta limbata, which does not smell of fish and has pale edges due to marginal soredia. It is less common than the other two Stictas.
The first picture's a bit pointless as it could be anything, but the vaguely haggis-like objects occupying the middle of the pic and just above are the rather scarce lichen Collema fasciculare. I've a genuine excuse this time as the tree was inaccessible and I had to shoot from a distance. The second pic is a little more coherent, and shows the "Floury Dog Lichen" Peltigera collina, which we did have once on the site way back. It is smaller than most Dog Lichens and is recognisable by its pale sorediate edge. The blurry bit at the bottom shows the dog-teeth on the underside (just in case you thought it looked the same as Sticta limbata!)
Most of these were on Willows, but the Lobarion community is also found on Hazel, Ash and old Oaks. Young Oaks are too acid.
These large lichens only develop after the tree has aquired a coating of bryophytes such as Frullania and Isothecium. Young Hazel stems are smooth and only have crustose lichens at first, many of which have their thallus under the bark.
Here is a typical young Hazel stem, with a variety of crustose lichens competing for space, producing a map-like effect. No bare bark is ever visible on stems like these, except in polluted areas. This community is called the Graphidion and the next 5 pics show some of its members. First is the greenish Pertusaria leioplaca
Thelotrema lepadinum, known as the Barnacle Lichen because the extra flap inside the margin gives the apothecium a barnacle-like structure (you can make it out on one or two in the pic). The pink lichen in the second pic is Arthonia cinnabarina, with the Barnacle Lichen above it.
Graphis scripta, after which the Graphidion community is named. It's an indicator of old woodland. And Pyrenula occidentalis, orange with shiny black perithecia, a species almost confined to the western fringe of Scotland.
Andy explained that as the Hazel stem matures, liverworts such as Frullania and Radula grow over these crustose lichens, as is happening in the RH pic above. These give a foothold for the leafy lichens of the Lobarion which eventually replace the crustose community. A naturally growing Hazel, neither coppiced nor grazed, will always put up new stems from the base and thus will have stems of all ages at any given time, allowing both the Graphidion and Lobarion lichens to transfer to new homes when their existing stems are no longer suitable.
Birch has a different community as its bark is more acid. Here are some of its members...
This lichen's fuzzy enough without my blurry picture making it worse. It's Ochrolechia androgyna, and is adorned, if that's the word, with greenish soralia The second one is its relative Ochrolechia tartarea which has nice clear-cut apothecia. Both these lichens were known as Cudbear and were collected in great quantity for dyeing wool. In Glen Nant not far from where we were is an abandoned settlement called Laraich a'Chrotail which means ruins of the lichen houses.
Pertusaria amara is a crustose lichen which can be distinguished from similar species by the bitter taste of the white powdery soralia. Menegazzia terebrata is hollow like a Hypogymnia but has small holes in the upper surface.
Other species seen on Birch were Hypotrachyna laevigata, Hypnogymnia physodes, Platismatia glauca, Sphaerophorus globosus (huge clumps!), Evernia prunastri and Usnea filipendula, all of which we've had on the site before.
Altogether 389 lichen species have been recorded at Glen Nant.
Shouldn't take long to find the rest of them then.
All photos and other content copyright © Carl Farmer