Geoffrey Haigh
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geoffrey311.bsky.social
Geoffrey Haigh
@geoffrey311.bsky.social
1.1K followers 250 following 440 posts
Lichen dabbler and photographer, Anapana-practitioner, sky watcher. I'm really here for the #lichens, but keep getting distracted by the wonderful #landscapephotography

And in an age of war and inhumanity, extremism and violence, I repost other things too
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geoffrey311.bsky.social
This really says it all. How dreadful.
#Gaza #Israel #Palestine #Genocide #Holocaust #Hamas
Take the worst thing you can say about Hamas, multiply it by 1,000 times and it still will not meet the Israeli repression and killing and dispossession of Palestinians - Gabor Maté, Holocaust survivor
August 17, 2025 at 9:04 AM
geoffrey311.bsky.social
substack.com/@bellavitafo...

#politics #Trump #USA #MAGA
August 8, 2025 at 7:31 PM
geoffrey311.bsky.social
#Gaza #Palestine #Peace #Israel
67 year old retired teacher arrested at a silent demonstration in Leeds for holding up a graphic reproduced from Private Eye magazine, making a joke around the banning of a non-violent organisation under #anti-terrorism laws.

See www.theguardian.com/world/2025/j...
Sign held up by elderly man at peaceful, silent protest, for which he was arrested by West Yorkshire Police. For those who cannot see the image, the sign, reads "'Palestine Action' explained. [cross] Unacceptable Palestine Action Spraying military planes with paint. [tick] Acceptable Palestine Action Shooting Palestinians queueing for food © Private Eye no 1653" Originally published in the satirical magazine Private Eye.
August 1, 2025 at 10:21 AM
geoffrey311.bsky.social
Exploring #lichens on #Isle-of-Rona, #Hebrides, #Scotland

I said once I had found 2 of the 4 former Lobaria species on Rona. Well, here’s no 3, Lobarina scrobiculata. I found this photo yesterday, I must have overlooked it before!

Tap/click the captions to expand.
#lichenGBI #FungiFriends #nature
A foliose lichen growing on a tree trunk. The upper sides of the lobes is a yellowish green, the undersides are very pale with a tinge of brown. This lichen was growing at a point I could barely see or reach on a mature birch tree, obscured from view by a big branch, and if I moved round the tree the ground fell away. I suspected it was Lobarina scrobiculata but wasn't sure. It was at the highest point I could touch, and pushed my camera up to it. Here's the photo. This species can be a blue-grey colour when it's hydrated, but in the hot dry weather while I was on Rona it had dried out to this pale green. These lobes are quite young – a good sign because it means it is growing – because there is no soredia on them. It usually produces grey soredia on the margins and the ridges. The upper surface is described as "scrobiculate" which means it has shallow depression separated by shallow, rounded ridges, and hence the name. The underside is pale with a pale brown tomentum. This brown tomentum on the lower surface is a key distinguishing feature from other Lobaria species. If you enlarge the upper left corner of the image, you can just see it. This means I've now found three of the four former Lobaria species that were recorded on Rona in 1990.
June 24, 2025 at 2:30 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, #Hebrides, #Scotland

Walking east past the old houses I came to a small rocky summit, on the island’s N–S ridge (at 48 m). Here were saxicolous lichens we’ve met before. Do you remember them?

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#lichenGBI #FungiFriends #nature
A dark brown foliose lichen with white pseudo-cyphellae on the lobes (remember yesterday's cyphellae?), with a number of apothecia down the left edge of the photo. Apothecia are the structures which produce the fungal spores by which this lichen reproduces. There is one small apothecium, closed up around the disc, and three much older, fully open discs, red-brown in colour. We saw this on rocks up near the summit of Meall Acairseid. On that occasion I did a K-test to check it was not another species I keep looking for. I did the same here. Having scraped away some of the upper cortex from one of the lobes I put a drop of KOH (potassium hydroxide) onto the white medulla of the lichen. It immediately turned yellow, then after a short time it turned red. If you're still scratching your head trying to remember this one, here is one clue. Foliose lichens with white pseudocyphellae along the margins and on the upper surface, many of them linear, usually belong to the genus Parmelia. This glossy dark brown species is Parmelia omphalodes. In NW Scotland it frequently covers the top of large boulders or rock outcrops. A pale brown fruticose lichen with some thick main stems and lots of much thinner side branches. This is a Sphaerophorus, but there are no fruiting bodies on this one (there often aren't) which give it both the name of the genus (Sphaer - ophorus = bearing spheres) and the name of this species (globosus). S. globosus is the one which has branches of varying thickness; S. fragilis has branches which all tend to be similar in thickness. I'm not sure we've met this one before on Rona. Here is a foliose lichen with quite narrow lobes, closely attached to the rock. Near the edge, at the bottom of the photo, are the younger lobes, the very youngest of which are a plain, pale yellow-green colour. There are no pseudo-cyphellae, but it is a similar and related genus to Parmelia. This is a Xanthoparmelia. The first part of that name comes from the Greek word xanthos, meaning "yellow". It is a very distinctive colour, which helps you start to identify it at first sight. Slightly older lobes, just away from the edge, have lots of dark dots on them. These are very small, thin, isidia. You need a 10x lens to see them properly. The oldest lobes, in the centre of the thallus (higher up in the photo) are simply crowded with isidia, so the surfaces of these lobes can no longer be seen. Scattered over these older lobes there are a lot of apothecia. The discs are again a red-brown colour, and are surrounded by a pale margin. Isidia are starting to grow from some of the margins of older apothecia, and some of the very oldest apothecia are being taken over by more isidia, where the disc once was. This is Xanthoparmelia conspersa. Conspersus is a Latin word meaning "sprinkled" – sprinkled with isidia. This lichen is common on well-lit siliceous rocks, both on the coast and inland. A number of Cladonias were growing on among moss on the edge of the rock. Cladonias with red apothecia always catch the eye, and often make for a striking photo. There are other Cladonias here. The narrow brown pointed spikes are one species, but I'm going to focus on that red-topped one. The stalks which bear the fruiting bodies (podetia) of some Cladonias end in a cup, but neither of these species do. The brown one ends in points, and the pale yellow-green one ends bluntly, with the red apothecia growing straight on the end. I think one short stalk branches into two just before the top, and each of those two branches has a red apothecium on top of it. The apothecia, remember, are where the lichen produces the fungal spores that are released into the atmosphere. There are four Cladonias in Britain that grow in the form of sticks and have red apothecia. To distinguish them from each other it is helpful to look at what the surface of the 'stick' (the podetium) is covered with. Two of the four have fine soredia on the podetia, so we can rule those out here. On the ground here there are a lot of small irregular bits of lichen. These are squamules, and it is from such squamules that the podetia have grown. To the right of the photo is another podetium, but with no red top. You can see how that one is attached to a number of squamules. You can also see much smaller squamules on the surface of the podetia. You might have to enlarge the photo to see them clearly. Apart from those little squamules, nothing else seems to be present on the surface of the podetia. Of the other two red-topped stick-like Cladonias, one (Cladonia bellidiflora) often has only dense squamules, the other (Cladonia floerkeana) can have quite a mixture of surface types, but it often has coarse granules. While it can sometimes be a bit tricky to tell the two apart, this all makes me fairly happy that this is Cladonia bellidiflora.
June 23, 2025 at 8:07 PM
geoffrey311.bsky.social
#Lichens on the #Isle-of-Rona, #Hebrides, #Scotland

“Primrose Alley” led to the ruins of an abandoned township. The houses were becoming covered with mosses and lichens. Today we focus on one special lichen, Sticta Sylvatica.

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#lichenGBI #FungiFriends #nature
The Sticta genus (or family of lichens) is related to the Peltigera genus. We looked at two Peltigeras over the last two days. I was excited to find several places where Sticta sylvatica was growing quite profusely, on rocks at the top of "Primrose Alley" and on the stones in the walls of the ruined blackhouses in the township. Sticta lichens are rather special because they are usually associated with old woodlands. They are members of the Lobarion community of lichens, which includes the four former Lobaria species, and other unusual lichens associated with ancient woodland. Like Peltigera species, Stictas have large foliose lobes. The upper surface is usually dark brown, from the cyanobacteria which is its photobiont. On the underside you can see a pale brown tomentum here. The really distinctive feature of Stictas is the presence of scattered cyphellae on the underside. Cyphellae are breaks in the lower cortex of a lichen thallus, forming a small round hole about 1 mm wide, through to the medulla. These breaks enable air and water vapour to enter the medulla. The small white shapes you can see here are these cyphellae. You may have heard of pseudo-cyphellae in Parmelia species. These are similar opening to the medulla, but they are called pseudo- ("false") because they occur in the upper cortex, not the lower cortex as here. This photo shows the upper surfaces of a few lobes of Sticta sylvatica. This is a multi-lobed Sticta; some species have only a single lobe per thallus. These lobes are a grey-brown colour. They become a darker brown when wet. These structures are about 5 cm long and up to 1 cm wide. On some of these lobes there is a faint network of ridges, made more obvious by the lines of isidia growing on them. Isidia are a darker brown and form on the margins and ridges of the lobes. This is its only method of reproduction since apothecia and pycnidia are never produced. Some species, including this one, Sticta sylvatica, have been called "stinky Sticta". One of the chemicals that the lichen produces is trimethylamine, which has a strong smell of fish. Some people can smell a Stictus as they walk up the the tree it's on. I can't, but if I handle a lobe when it's wet, my fingers then smell of fish.
June 22, 2025 at 6:07 PM
geoffrey311.bsky.social
Hi Erik, Have you found the website of the British Lichen Society? There are lots of wonderful resources there. The society has members worldwide. Check the learning tab on britishlichensociety.org.uk. The Lichen Chat zoom group and the Lichens for Absolute Beginners courses could be good for you.
June 22, 2025 at 4:42 PM
geoffrey311.bsky.social
#Isle-of-Rona, #Hebrides, #Scotland

The trees in “Primrose Alley” also had plenty of interesting #lichens on them. Some we’ve seen before, but new people “like” these posts each day. Welcome! Come and enjoy the little things in #nature.

Tap/click the captions to expand.
#lichenGBI #FungiFriends
Growing on a horizontal branch of a tree was this distinctive lichen. It's quite abundant in some parts of Britain, but is also quite beautiful. This is Parmotrema perlatum. If you enlarge the image you'll see what's distinctive about it, in case you find it in the woods on a broad-leaved tree. It's a foliose or leaf-like lichen which may be pale grey to pale green, depending on how hydrated it is. The underside of the lobes is dark, brown near the margins and black in the centre. The lobes are attached to the bark by rhizines in their centres. See how the margins of some lobes are covered with a thick pale substance. This causes them to fold into short, tight bends. The substance is fine soredia. It's composed of very small clusters of both the fungal cells and the algal cells of the lichen. When they become detached, if any of these clusters ends up in the right sort of place, they can grow into a new lichen. Yesterday we met one of the "dog-lichens", Peltigera membranacea. Here it is again, with another Peltigera. This new one is quite common on soil, moss, rocks and tree stumps. The P. membranacea is just right of centre. Like yesterday's example, these lobes are completely covered with a white tomentum. You can see too that the surface of the lobes is uneven, with some raised areas. And see how the margins turn downwards at the very edge. Then there are some lobes of Peltigera hymeninum. They are a bit old and somewhat broken, but you can still see their main features. These are the brown lobes. They have no tomentum, nor do they have the distinctive raised areas of the P. membranacea (better seen in yesterday's example) These lobes are much thinner than the P. membranacea, which may be why these ones have become rather broken. Notice too that the very edge of the lobes curls upwards rather than bends downwards – that is, where the lobes still have their original margin left. When looking at a Peltigera, you always need to look at the underside to pick up more characteristics that help identify it. These lobes are showing their undersides very clearly. They may look rather bland and nondescript, but there are some important features here. They have veins as all Peltigeras do. These ones are rather indistinct. They are shallow and broad, and their colour is pale and subtle. But they are not white like the very distinct veins of P. membranacea. They form a network, and in the gaps between them you can see the undersurface of the lobes is distinctly white. A few rhizines can be seen in the lower part of two of the lobes. They come from the veins, they're pale, thin and occasionally splitting. Their job is simply to anchor the lobe to the moss it's growing over. And finally for today, if you missed this lichen before, here is some Lobaria pulmonaria growing exuberantly over the low branches of an old willow tree. The weather was dry; when it's wet these lobes are a much brighter green. Lobaria grows in damp, humid woodlands, but it doesn't cope with atmospheric pollution. These conditions are just what we find on the west coast of Scotland, where it grows very happily. These lobes are big. Some may be 12 inches or even more long, and several inches wide. Some of these lobes are turning their undersides towards us. There are some very big lobes in the upper part of the picture, left of centre. There is another one hanging off that branch at the bottom of the picture. These lobes are only attached to the tree at one end, the rest is free. See how the undersides have some white islands within a pale orange-brown network. Those islands are raised, and they correspond to depressions on the upper side of the lobes. The pale brown parts are covered with a brown tomentum. Looking at the green or brown upper sides you can see the depressions, outlined by raised ridges. In some cases the ridges stand out because they are picked out in white. This species produces isidia along the ridges and margins of the lobes – though occasionally a few specimens produce soredia in place of isidia. When the isidia break off they leave white scars behind.
June 21, 2025 at 8:45 PM
geoffrey311.bsky.social
No, sorry, not isidia. Isidia are like little pins or rods growing out of the surface of the lichen. This very lumpy, bumpy thing, this is the surface.
Isidia on Parmelia saxatilis – small and narrow, pin-like Isidia on Pertusaria corallina – dense, cylindrical, even branching Close up of the isidia on Pertusaria corallina Isidia on Pseudevernia furfuracea, at different stages of growth
June 21, 2025 at 2:20 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in #Scotland

In the next few posts I’m going to retrace a walk across the island, and show the lichens I found on the way. We start today with a boulder in “Primrose Alley”.

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#lichenGBI #FungiFriends
Here's a large rock lying beside a grassy path and beneath a number of large old birch and willow trees. You can see why I nicknamed the path as "Primrose alley". The rock is a piece of Lewisian gneiss, an ancient metamorphic rock. There are some bare patches on the rock, but much of it is covered with moss and lichens. Look closely and you'll see three different lichens here. All three often grow on trees, but are sometimes found beneath the trees on rocks in humid environments. The one to the left is Lobaria pulmonaria, which we've looked at in previous posts. The pale grey lichen to the right is a large, foliose species. It's a species of Peltigera, and it's one of the most common Peltigeras, at least in the north and west of Britain. Peltigera membranacea is a woodland species and grows among moss on the ground, on rocks and at the bottom of tree trunks. The upper surface of the lobes is usually grey or brown-grey, but may be covered with a thick, white tomentum, usually just towards the margins. This is a layer of short interwoven or coiled fungal hyphae with a texture similar to velvet. These lobes are completely covered with tomentum. Each lobe may be about 2 or even up to 4 cm broad. The lobes turn down a little at their margins. Notice also the raised areas of this upper surface, looking a bit like blisters. Such lobe surfaces are described as "bullate". If you find a Peltigera and wonder whether it may be P. membranacea check for large lobes, grey or grey-brown, with a bullate surface and white tomentum on at least part of the surface. But if you find lobes that answer to this description, but have some flattened isidia on their margins and beside any damage to the lobe, this will not be P. membranacea, but a similar species, P. praetextata. But then turn a lobe over to look at the underside. It isn't always easy to see the underside of a lobe, especially if those long dangling rhizines are doing their job and anchoring it firmly to the moss. But this lobe was largely loose, so it was easy to lift it up and look. There is a series of radiating raised white veins on the underside, and from those veins a series of rhizines grow downwards. These are simply a way of anchoring the lobe to the moss it's growing over. They are not roots. Lichens are not able to move water around their bodies. They absorb the water they need from water vapour in the atmosphere. The underside of Peltigera membranacea is completely white. It doesn't have coloured veins like some species. And the rhizines are quite thin and simple. They are not bushy. These two features confirm that the Peltigera you're looking at is this one, P. membranacea. The underside of Peltigera lobes do not have a surface layer. Most foliose lichens have a "skin" or cortex on both the upper and lower surfaces. In this case there is no cortex over the lower side of the white fungal medulla that makes up most of the thallus or "body" of this lichen. As a result, air and water vapour can be absorbed easily. They will be used by the cyanobacteria just below the upper surface as they photosynthesise. Here's a third lichen growing on this boulder, a darker grey one. At the bottom you see some small lobes of the Peltigera growing over it. Then there are some more grey-brown lobes, but these are smooth and very thin. The area in this photo is only 3 cm wide (see mm scale at the top). The plain edge-lobes of this lichen are only 5–6 mm wide. More mature lobes away from the edges are largely covered with some small grey-brown "balls". These are globular isidia, an outgrowth from the lobes containing both fungal cells and cyanobacterial cells, ready to grow into a new lichen if they are detached and end up in a suitable place. This lichen fooled me for a while. The weather was so dry and sunny every day, so it had dried up and looked an opaque grey. But I couldn't think what it could be. It was only when I brought a sample home, and sprayed it with a little water to rehydrate it, and then put it under a microscope that I began to realise. The microscope lights were shining through the lobes which had become translucent. It's a "jelly lichen" I realised. Then I ran it through a key and discovered it is Collema subflaccidum, a reasonably common woodland species, but the first time I had come across it.
June 20, 2025 at 5:34 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in #Scotland

Above the black and orange zones of coastal lichens is a grey zone of lichens with muted colours. This gradually gives way to the normal inland lichens.

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#lichenGBI #FungiFriends
There are two species of Ramalina that are found on coastal rocks. This one is Ramalina cuspidata. If you enlarge the right-hand branches of the lichen in the foreground you'll see a lot of black dots along the branches, all at the tip of small white swellings. These are pycnidia, one type of spore-producing structure. In the centre of the photo a circular structure is attached to another of the branches. This is an apothecium, a second type of spore-producing structure. A number of features help to identify Ramalina cuspidata and separate it from Ramalina siliquosa (which will be in the next photo). 1. Its branches are narrow and either flattened or ±rounded in cross-section. 2. The branches are blackened right at the base, as they arise from the holdfast on the rock. 3. The conspicuous black pycnidia we've already seen. Ramalina cuspidata also tends to occur lower down on the shore than R. siliquosa. Here are the flattened branches of Ramalina siliquosa, which are quite stiff and sturdy. Usually flattened, they may be between 2 and 9 mm wide. Both Ramalinas are very common on coastal siliceous rocks, as well as exposed sites further inland such as wind-exposed outcrops of rock, hilltops and tall buildings where salt-laden winds may encourage their growth at the expense of more salt-averse species. Ramalina siliquosa may be distinguished from R. cuspidata by several features. 1. Branches stiff and tough, usually flattened except at their base, up to 9 mm broad. 2. No blackening at their base (though beware of dirt!) 3. Pycnidia are frequent and may be clustered into small nodules, but they have white tips. There are some black specks of dirt on this specimen, but most of them are found on the flat surfaces of the branches, not on the white pycnidia. More of this black dirt is found on the base of the branches, but it does not look like a general blackening of the stem. If in doubt, spray or pour some water over the lichen to wash away any dirt. The grey zone can include quite a number of different species, and I can only illustrate four in this post. Here, some very long, thin, branching brown lobes of a foliose lichen spread out across the rock surface. When wet it undergoes a startling colour-change. It loses the brown colour and appears as dark green instead, as the algal cells become visible beneath the transparent surface layer, the cortex. This is Anaptychia runcinata. The generic name means that it occurs on (ana) the Greek island of Ptychia near Corfu, now known as Vido. This lichen can be abundant on hard coastal rocks, and also on turf and soil. The lobes are up to 2.5 mm wide, slightly wider at their tips, fairly thick, flat to concave. Thick white crustose lichens with round black apothecia but white margins are common on coastal rocks, and may belong to one of two species. These two look almost identical and distinguishing one from the other calls for a little investigation. The best way to distinguish them is to cut one of the apothecia vertically into two pieces. It's easy to cut as it has the consistency of a mushroom (it is a fungus after all). The difficulty is that the apothecia are very small, only 1 or 2 mm wide. Use a (single-sided) razor blade or a sharp pen-knife, don't lose sight of the cut apothecium, and then use a lens to view the cut surface. If the layer just below the black disc is also dark (it may have a purplish sheen), the lichen is this one pictured, Tephromela atra. If that layer is pale (it may have a greenish colour), the lichen is the very similar looking Lecanora gangaleoides. Sometimes the two will grow together.
June 18, 2025 at 7:51 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in #Scotland

Further up the #coast, the black zone is overlapped by the orange zone, which also extends into the grey zone. These lichens experience less splashing but still plenty of sea spray.

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#lichenGBI #FungiFriends
Coastal rock covered by a mixture of lichens. Much of it is black, this is the Hydropunctaria maura we've seen before. On top of the black there are pieces of two bright yellow-orange species, one foliose and one crustose. There are also small pieces of a much more orange species scattered about. Pale grey and white lichens are also represented. This is quite a mixture. One of the most prolific lichens to be found in the orange zone is this one. It's a foliose lichen, often with thin, narrow, strap-like lobes, though as they age they do widen and become more rounded, as in the previous photo. This is Xanthoria aureola, a relative of the very common Xanthoria parietina that many of us will be familiar with in urban and agricultural settings. Sometimes it is difficult to tell the two species apart. X. parietina usually has lots of round orange apothecia while X. aureola has them much more sparingly. Any coastal lichen with narrow strap-like lobes like these will be X. aureola. Even when these lobes grow fuller and wider, they rarely overlap each other, while the lobes of X. parietina usually overlap densely. Here is a bright yellow-orange crustose lichen growing over the black H. maura near the top of the black zone where it overlaps with the bottom of the orange zone. See the very long marginal lobes. This is a placodioid lichen, that is a crustose lichen with marginal lobes. Unlike the lobes of foliose lichens, these cannot be separated from the rock beneath them. As a crustose lichen, it has no lower surface; its fungal hyphae penetrate into the rock. This is Flavoplaca thallincola. It often prefers the shade or north-facing rocks. It usually produces plenty of apothecia on the central area, but they seem to be absent here. The distinctive reddish-orange colour of the small, scattered lichens in the first photo is often enough to identify it as Flavoplaca marina. I've only found this photo of a rather poorly-developed specimen from Rona. Here many parts of the thallus are separated from each other; small patches of a continuous areolate crust are found in only a couple of places. Quite a number of small, young apothecia can be seen. These grow to about 0.8 mm wide, but compare these ones with the mm scale. The discs can already be seen to be a deeper orange colour.
June 16, 2025 at 8:42 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in #Scotland

Today we move up the coast to the High Water Mark. The black zone extends from just below to above the HWM. Here are two black lichens commonly found there.

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#lichenGBI #FungiFriends #coast
This is the black crustose lichen that is mostly responsible for that prominent black zone around the coast. This is Hydropunctaria maura. In Latin, maura means dark or black. At the top of the zone there is some overlap with the orange zone, hence the appearance of the yellow lichens here. We'll look at those tomorrow. Can you see a second black lichen here? The surface of the H. maura is often slightly roughened, or it may be glossy. The crust is usually divided into small, neat areoles by cracks that develop in it. Perithecia vary from almost entirely immersed in the thallus, to being quite prominent. Here are some prominent perithecia, each with a small black ostiole. Perithecia are flask-like chambers where the fungal spores are produced, and the ostiole is the hole at the top of the flask through which they are released. Again, you can see the pattern of cracking into small neat areas. This is Lichina confinis, a small fruticose lichen that also grows in the black zone on rocky coasts. This example is only 1.5 cm wide (scale in mm). The small branches grow to no more than 5 mm high; these ones were rather shorter. It is common on coastal rocks, especially on sunny, sheltered shores. You can also see the roughened nature of the surface of the Hydropunctaria maura here, and how the cracks develop in it. There is an area of new crust just below the left side of the Lichina, with very few cracks, but the divisions become more regular in older crust. Here is another example of Lichina confinis, this time showing the apothecia clearly. They are the small globes at the tips of the branches, and grow up to 0.5 mm wide.
June 15, 2025 at 7:32 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona in #Scotland

A special set of lichens grow on coastal rocks, where they must cope with varying amounts of salt water splashing them or covering them. They grow in coloured zones on the rocks

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#lichenGBI #FungiFriends #coast
Blue sea at the bottom, below steep coastal rocks, then a rough grass and heather hillside, with blue sky at the top. Some of the colours on the rocks are the lichens growing on them. A black zone is usually found on rocky coasts, just above the high water mark. This is not a deposit of spilt oil, but a black lichen growing on the rock. Above the black is usually an orange zone. A number of orange lichens grow there, able to cope with salt water splashing them, but not as well as the black lichens. The orange zone grades into a grey zone, of lichens able to cope with sea spray but not direct regular splashing. The grey zone then slowly grades into lichens usually found on inland rocks. The sea may still influence the lichen flora for a mile or more away from the coast. Below the black zone is the barnacle zone where the rocks are submerged twice a day. Other lichens may sometimes be found between the high water and low water marks. No lichens grow below the low water mark, where rocks are permanently submerged in the sea. In this post we look at a couple of lichens found in the lowest, the intertidal zone. Rocks partially covered with a smooth olive green coating, with two barnacles growing on it. The smooth green coating on these rocks is the lichen Wahlenbergiella mucosa. The name reflects the fact that the original type specimens were collected by Göran Wahlenberg from northern Europe. The surface is smooth and shiny, without cracks. Its colour can vary from olive-green when growing in shaded places (as here), to black when in direct sunlight. A close up view of a piece of rock coated with Wahlenbergiella mucosa. The lichen is black on the top, horizontal surface where it receives much sunlight, but dark green on the vertical surface which is shaded from the sun. Little detail can be seen in the lichen, which forms a smooth, shiny coating on the rock. The lichen reproduces by means of fungal spores, produced in perithecia. These are immersed within the lichen and do not protrude from it. Sometimes the tops of the perithecia may be visible as a series of small black dots, though I cannot see any in this photo from the east coast of Rona. A close up view of a single barnacle, which fills much of the frame, though parts of two other barnacles can be seen behind it. All three are attached to rocks that are pale orange in colour and partially covered with the dark olive-green of Wahlenbergiella mucosa. The pale orange may be an alga growing on the rock. On the shell of the barnacle numerous very tiny black holes may be seen, no larger than 0.25 mm across. These tiny pits are the only evidence that a lichen is living embedded within the shell of the barnacle. The lichen is called Collemopsidium foveolatum and is common around the shores of Britain and Ireland, except in parts of the south and east of England where rocky coasts are not found. There are other species of Collemopsidium where the perithecia are more visible on the surface, but this was the only species I was able to find on Rona. Wherever barnacles, limpets or other shells are found, it is worth looking closely with a lens to see whether any have this lichen.
June 14, 2025 at 7:39 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona in #Scotland

Umbilicaria species grow on hard exposed rock in mountain environments. They are unusual foliose lichens since they are attached by a single, often central holdfast. I found two on Rona

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A small reddish-brown multilobed thallus just over 2 cm wide (scale in mm). There were many of these small thalli dotted over the rocks at the top of Meall Acairseid ("Anchorage Hill") which at 125 m was the highest hill on Rona, overlooking the main harbour. This is Umbilicaria polyrhiza. The upper surface is smooth and plain. Black rhizines can be seen poking out around the margins and where there is any damage to the lobes. What are rhizines doing on a lichen which has a central holdfast? Well, they play no part in attaching the lichen to the rock, and so technically they are called "rhizinomorphs", structures in the form of rhizines. What role they may play in the life of this lichen, I have never heard. A larger example of Umbilicaria polyrhiza at 4 cm wide. The same plain, smooth upper surface to the lobes, but more of the black undersides with their black rhizinomorphs can be seen. A rather different Umbilicaria. This one was less frequently found, but it was again on the rocks of Meall Acairseid. This is Umbilicaria torrefacta. Its name come from the Latin word meaning to parch or roast, and refers to its very dark colour. This is a single-lobed lichen, though as you can see it is much crumpled. It can be identified from its torn margins and from a series of holes close to the margins. This gives the margins rather a lace-like appearance. Here are the two species growing next to each other on top of Meall Acairseid. Umbilicaria torrefacta is on the right, Umbilicaria polyrhiza on the left, with a further U. torrefacta on the far left. Notice on the U. torrefacta not only the crumpled nature of the lobe and the lace-like margin, but also the many apothecia growing on its upper surface. And notice the very complicated structure of the apothecia. Rather than a plain circular margin surrounding a disc, these apothecia have what's called a "gyrose" structure. The margin is folded back and forth several times across the disc, which is barely visible between the folds. See too how these Umbilicarias are able to grow over the crustose lichens coating the rock unopposed. As foliose lichens they can simply grow over the top of the crustose species. The one with yellow areoles is Rhizocarpon geographicum. The very pale brown one is Fuscidea cyathoides, both common crusose species on silicious rocks.
June 12, 2025 at 8:05 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in the #Hebrides, in #Scotland

I found two Stereocaulon lichens while on Rona. One was on the large boulder, the other on an adjacent outcrop. Come and take a closer look at them.

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Stereocaulon lichens are mostly found in upland areas growing on siliceous rock. The name means a stiff or solid stalk, and it refers to the podetia which grow out from the rock. This lichen is similar to Cladonias in having two thallus forms. First a crustose or squamulose primary thallus develops, but that usually disappears early. Then a fruticose secondary thallus develops, of stalked and richly-branched, usually erect, podetia – or, pseudo-podetia as we ought to call them, for unlike podetia on Cladonia species, which are hollow, these ones are solid. These pseudo-podetia are a little like the branches of shrubs which are covered in leaves – or in this case, with tiny phyllocladia. To identify the species we need to study these phyllocladia. Use a 10x lens, a microscope, or (in this case) take a high-resolution close-up photo. This one is Stereocaulon vesuvianum. I've heard two explanations for the name. One, rather fanciful, is that the pseudo-podetia resemble a column of steam or ash rising from Mt. Vesuvius. But I don't think they do. The other, more mundane, is that the species was first found and described on the slopes of Mt. Vesuvius. S. vesuvianum is the most common species in the UK. If you find one, it may well be this species. Now you have to make sure it is. To do this take a close look at the little phyllocladia on the long stalks. Some of them at least, more likely those growing in the shade, have thick white margins and a darker, grey-green "window" in the centre. In this photo you can see that in the phyllocladia in the shadows at the top right, and in the middle right. The algal cells are found in these phyllocladia, and the "window" allows the light to reach them. Another feature here is on the illuminated stalk just below and right of the centre. See how the end of it is bare, without phyllocladia, but right on the tip is a ball of soredia. This Stereocaulon looks a bit different. The most obvious difference from this distance is the presence of lots of dark brown apothecia. Try enlarging this photo to take a close look at the phyllocladia. They are white and round; there are no "windows" to be found here. There is one brown apothecium in this photo. These phyllocladia grow into cylindrical forms, sometimes branching like very little fingers. They are only 1 mm long though. You might think of them as very tiny "hands". This is Stereocaulon dactylophyllum. It can often be recognised by the abundance of dark brown apothecia. But even if those are not present, the colour and shape of the phyllocladia still enable it to be recognised.
June 10, 2025 at 6:57 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in #Scotland

Not all lichens are easy to recognise. Between the foliose and fruticose lichens, between the colourful ones, the surface of a rock is often covered with grey or white crusts.

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Here are two crustose lichen on the big boulder, both fairly nondescript, one off-white and one pale grey. You can waste a lot of time with that sort of lichen. If you can't get anywhere with them, you need to walk away and look for something a bit more distinctive. However, these two are both distinctive in their own way. It's just a matter of knowing what to look for. But first, that black line down the middle of the photo, between the two lichens. That isn't a prothallus; it's a zone of conflict. Neither lichen wants the other one to encroach on its space, let alone steal its algae. The black zone creates a boundary where they can hold each other at bay. Let's start with the one on the left. With an unknown lichen, start by describing it as carefully as you can. What exactly do you see? Start with the obvious, and move onto less obvious details. It's a crustose lichen, it's cracked into small irregular areas (areoles) by cracks which reveal a black hypothallus. The areoles are not smooth. Try enlarging the photo. The closer you look, the more you see. The whole surface is made up of small warts ("like fossilised porridge" as one writer put it!) There are no isidia or soredia, but there are usually plenty of black apothecia. As they grow older they get bigger, up to 3 mm across, and the more irregular the white margin becomes. This is Tephromela atra, a common lichen on rock; now you may feel you'd recognise it anywhere. But there's a catch - another lichen called Lecanora gangaleoides looks very similar. And sometimes they grow together. How can we distinguish them? Chemicals won't help much, both are C– and K+ yellow. The trick here is to cut one of those big black apothecia in half, and look at the cut surface just under the black top. If that is dark (maybe with a purple sheen) it's this lichen. If it's pale or greenish, it's the other one. Another job for a small knife or a razor blade. Now lets try the pale grey lichen on the right. The scale here is in mm, the whole photo covers an area of lichen just over 1 cm high. But this magnification shows the details. Again, try to describe it. It is crustose, fairly thick again, and cracked irregularly into small areas. It's pale grey, and looking down the cracks a black hypothallus can be seen. This time the surface is smooth, not warted. Again, there's an abundance of apothecia, and although they are dark, they're quite different from the last lichen. There isn't the same contrast between jet black discs and thick white margins. These are varying shades of grey. They are on the surface of the thallus, but not on top of or above it. These too start circular, and though they become more irregular, they are nothing like Tephromela atra with its sinuous margins. One detail picks this lichen out as distinctive. Notice the younger, more circular apothecia have rather white margins, but as they age so the margins darken, until they are the same colour as the surface of the thallus. This is Circinaria caesiocineria. It's widespread especially in N and W Britain, usually on nutrient-enriched rocks (bird poo!) especially near lakes or the coast. So if you're stuck with an unknown lichen, try looking as closely as you can – take a detailed close-up photo if possible – and then describe it. That can be fun in itself and you'll learn a lot from it. But once you've got all the details clear in your mind you can then go to the lichen books, or even to other people's photos, and compare them with what you've found. Only now will you know exactly what you're looking for.
June 9, 2025 at 7:53 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in the #Hebrides, in #Scotland

One image today, showing the interactions between three lichens on the sunny side of the large boulder I was exploring.

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Here are three lichens jostling for position one one part of the boulder. At the bottom, perhaps the oldest one, is Rhizocarpon geographicum, the Map lichen. "Geographicum" is formed from two Greek words meaning "to draw" and "the earth", i.e. to draw a map. Its greenish-yellow (or yellowish-green) colour is familiar to many people in the hills. Looking closer, the crust is broken into small areas called areoles, and the black hypothallus (the very lowest layer, attached to the rock) is visible as black lines between the areoles. This lichen does not look healthy. Parts of it have turned black where they have died. I've searched the image for its apothecia, but I don't think I can find any. And two other lichens are growing over it - the large pale one at the top, and some pieces of a brown one in places. The large pale lichen is also divided into small pieces separated by black lines. It's quite a thick crust, and from this angle we can't quite see to the bottom of some of the cracks, but where we can, it also has a black hypothallus. Look also at its apothecia. They are sitting on top of the areoles. See how contorted the margins of some of them have become. This was a very common lichen which I found on nearly every rock on Rona. It's Fuscidea cyathoides, and sometimes it forms large mosaics. Then there's the brown lichen. It's formed of small separate pieces, like separate plates. These are almost crustose, but not quite. Look at the top right especially, and then back at the other ones. They are not fully attached to the rock but have free edges lifting from it. These are separate squamules. It's a squamulose lichen. Its apothecia are very small, and they don't stand on top, but are immersed in the squamules. The discs are darker than the squamules, and usually slightly depressed in it. This is Acarospora fuscata. In some places it looks like it's holding its own against the Fuscidea. In the middle it seems to have grown over the Rhizocarpon.
June 7, 2025 at 7:11 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in #Scotland.

Beyond the aspen trees the track climbed up.
At its highest point (only 100m) a huge boulder sat beside it, covered with lichens that grow on rock: saxicolous lichens.

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Here is the boulder, made of Lewisian gneiss. It has sat here ever since the ice deposited it at the end of the Ice Age, and for ten thousand years lichens have been colonising the parts of it each finds most congenial, jostling each other for space, growing over each other, dying off and being replaced by others. Now, every inch is lichen-covered, and I spent a happy hour or two exploring all over and around it. The top of the boulder was largely covered with this very dark foliose lichen. Its lobes are a similar size and shape to the pale grey-green ones we found on the birch tree on Monday, and they also have some pale pseudo-cyphellae. There are not many in this photo, but there are some, along the lobe margins and some very small ones on the lobe surfaces. This is another Parmelia, Parmelia omphalodes. The Parmelia omphalodes group is conventionally divided into three species, one of which doesn't occur in Britain. Of the other two, I've been looking out for Parmelia discordans for a long time, but never found it yet. This particular specimen looked promising. P. omphalodes usually has a lot more pseudo-cyphellae on the surface of its lobes. I had to check this one out. The real difference between the two species is their chemistry. Each of them produces a different chemical in their medulla (the white layer beneath the dark brown surface layer). This called for what lichenologists call a K test. "K" here stands for Potassium hydroxide, KOH, an alkali which reacts with the acid produced by the lichen, to form a coloured salt. My technique is to use a razor blade to scrape away some of the dark brown layer from one of the lobes. Once the white medulla has been exposed it can be tested. A single drop of K is really much too large: it would flood much of a lobe and likely react with the brown layer as well as the white one, leaving the result confused. So a drop of K goes on some convenient surface (the blade of a knife in this case), and a minute amount was then picked up on a corner of the razor blade. That tiny amount was then placed precisely, in the middle of the exposed medulla, and I watched it through a lens. It turned yellow, then after a short while it turned red. Ah, salazinic acid – Parmelia omphalodes after all. Another foliose lichen on part of the top and sides of the boulder. This is a very common lichen that grows on rocks, trees, bare wood, just about anything it can find. And it's not fussy about air quality either; only in the most polluted areas is it absent. This is Hypogymnia physodes. The upper surface of the lobes is pale grey, the underside is black, and, as here, you can often see the black colour from above, creeping round the edges of the lobes. Hypogymnia means "naked below"; there are no hairy rhizines attaching the lobes to the rock, only some sticky pads. Each lobe spreads out into a series of "fingers". They are actually hollow, and open at the tips. This enables air to circulate inside the lichen. And around the openings soredia is often found – little bundles of fungal cells and algal cells, ready to grow into a new lichen if they end up in a suitable place. In this view from above, little soredia can be found, but a few odd grains are visible. The scale underneath is in millimetres. Here is a fruticose lichen, growing in the full blare of the Hebridean sun on top of the boulder. It's tiny, it was no more than a centimetre high. The brown colour is probably a form of sun-shade to protect the algal cells just below the surface layer – just as with the Parmelia omphalodes. If you enlarge the image and look closely at the tips of these little "branches" I think you can see some black, globular structures on some of the tips. These are pycnidia, a spore-producing structure. This is Cornicularia normoerica. These little branches are stiff and shiny. It usually grows in windy mountain situations, on well-lit coarse-grained siliceous rocks.
June 6, 2025 at 7:56 PM
geoffrey311.bsky.social
Exploring #lichens on the #Isle-of-Rona, in the #Hebrides, in #Scotland

The old aspen tree held two more treasures, a Nephroma, and one you'll recognise if you've been following this series of posts.

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These pale grey lobes are Nephroma laevigatum. Their colour depends on their state of hydration, pale grey when dry and reddish brown when hydrated. This is a special lichen because it is associated with old woodlands. It is often associated with Lobarias and other old woodland indicators. Many of the trees on Rona were not of any great age, they were mostly young silver birch trees, but small pockets of older trees could be found here and there. This old aspen tree must have stood beside the cliff for many years and was still hosting the lichens to show it. People moved onto Rona in the 1840s when they were cleared from Raasay to make room for sheep. The population dwindled in the early 20th century, and many moved back to Raasay when they could. The last inhabitant left in the 1940s. Yet the island manager told me every piece of flat land on Rona had been cultivated at one time or another. Whatever woodland cover the island had had must have been largely cut down, which fits in with the observation that only pockets of older trees can now be found, on more marginal land. The lobes of this lichen, whether brown or pale grey, are smooth. Laevigatus in Latin means smooth or polished. You may see some wrinkling here or there, but otherwise the name is apt. The underside of the lobes is white. Apothecia are common on this lichen, but what is rather unusual is that they are found on the underside of the lobes. The lobes bend backwards to reveal them, but the best view of them always comes from looking up the trunk of the tree on which the lichen is growing. When you look at these brown apothecia, notice that many are wider than they are long, and some are slightly curved into a kidney shape. "Nephroma," the name of the genus, comes from the Greek word for a kidney, νεφρός. And if you're familiar with some Peltigera or "dog-lichens" these lobes and their apothecia may also look a bit familiar. The two genera are related. Both have large lobes, and both have rather similar looking apothecia. The difference is that where the Peltigeras have their apothecia on the top surface of the lobes, Nephromas have theirs on the underside. Just beneath some Nephroma laevigatum are some lobes of Lobaria pulmonaria. They are small and young, but it's good to see that they are there and are growing. In the right conditions, in a very clean and unpolluted environment, this is a lichen that grows prolifically. Just check the lobes for isidia, and for the white scars where isidia have fallen off. There are no apothecia yet. One estimate I saw recently suggests it takes about 35 years before the lobes will become fertile.
June 5, 2025 at 6:45 PM
geoffrey311.bsky.social
#lichenGBI #Scotland #fungi-friends

Past the old birch tree on the #Isle-of-Rona, and other birches, there was a small group of aspen trees at the bottom of a cliff.

I scrambled up between the largest one and the cliff. There I found many special #lichens on it.

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This is Pannaria rubiginosa, growing as a large patch some 8 or 9 inches across on the rough bark of the old aspen tree. See how it is growing on a thick, black mat, a hypothallus made of fungal hyphae. On that are some narrow, branching and indented squamules a pale grey colour with white margins. This is not a continuous foliose lichen. It has many apothecia. Their discs are a red-brown colour and their pale margins are not smooth but "crenulate" – like the crenulated walls of a medieval castle. Here is a closer look at the edge of this lichen. Here you can see the black fungal mat more clearly, the pale grey squamules with upturned, indented, white margins. You can see the jam-tart style apothecia with their slightly convex discs and crenulate margins. Some very young apothecia are starting to form on the nearest squamule. I was looking up to this lichen. Below it on the tree trunk there is a green and brown liverwort, and a very pale green leprose lichen. Leprose lichens are diffuse with no clear margin and no cortex. They are made up of small soredia-like granules, each containing both the fungal and algal partners. They are difficult to identify to species level, and I won't attempt that here. This lichen is not a Pannaria but a Pectenia. It too grows on a thick, black mat of fungal hyphae forming a hypothallus, but rather than a series of separate squamules, this one is much more of a foliose lichen. Look at the outer lobes of this lichen. They have a series of darker, concentric drops or depressions, and thin, light radiating lines. These, together with the few red-brown apothecia here, suggest this is Pectenia cyanoloma. Here is more of an edge-on view of the lichen, showing the thick hyphal mat better, and some more of the apothecia, some of them quite complex. Their margins, though contorted, are smooth, not crenulate. This lichen has a problem. Lots of small black dots on its surface suggest it has been invaded by another fungus. These black dots may be the tops of perithecia, the fruiting bodies of the other fungus. Parts of the lichen are turning black where they are dying. Fungi that grow on or in lichens are called lichenicolous fungi. Not only is another fungus using this lichen as a host, so too is another lichen. At the bottom of the photo, both on the black mat, and on a lower lobes, are a number of small green squamules of a lichen called Normandina pulchella. Unlike a fungus, a lichenicolous lichen does no harm to its host. It simply uses it as a surface on which to grow.
June 4, 2025 at 6:35 PM
geoffrey311.bsky.social
Here are three more #lichens from the birch tree we've been exploring on the #Isle-of-Rona. Two are fruticose (bush-like); the last is a rather special foliose one.

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One trunk of the silver birch tree with moss and lichen growing on it. All the lichens are bush-like, and all are a similar pale green colour. But they are not all the same. Most of the lichens have flattened lobes or branches while the one at the bottom has rounded lobes/branches. Those higher up in the photo are a species of Ramalina; the lowest one is a species of Usnea. This is a thallus of the Ramalina lichen. If you enlarge the end of the branch hanging down in the centre of the photo you'll see an open sort of area on it, part of which contains some very small, pale dots. It's after the branch turns right, near the tip. Once you've found this one you may begin to see similar areas containing pale dots elsewhere. These dots are small pieces of soredia. Each one is like a little ball made up of fungal cells and algal cells. Once they become detached they are ready to grow into a new lichen, if they end up in a suitable place. The hollow places which hold them are known as soralia. These two names can be a bit confusing. Soralia are the places where soredia form. The soredia on this lichen are particularly small, and are often compared with grains of flour. Farinaceus is the Latin word meaning "like flour", so this lichen has been named Ramalina farinacea. This is not a Ramalina, though at first sight it may look rather similar. Notice how all the branches, both the thicker main stems and the thinner side branches are round, not flat. I'm pushing it to one side with my thumb because I wanted to get a view of the holdfast, the place right at the base where it's attached to the tree. Some Usneas have a very black area near the holdfast, as if they've been coated with tar. This one does not, it has a pale holdfast. This, along with several other clues enable me to identify it as Usnea flammea. Usnea is a very distinctive genus of lichens, bush-like with round stems and branches. The features you have to look for to identify which Usnea you've found are quite distinctive, rather unlike those of other types of lichens, even though some of them may have soredia, isidia and apothecia. The name Usnea probably comes from an Arabic word, Ushnah, meaning moss. One species was known to Persian and Arabic doctors in the Middle Ages and had a medicinal use. Just before I left this tree I was rather excited to find three rather small thalli of this lichen. The scale at the bottom is in millimetres; the whole lichen is no more than two and a bit centimetres long. One was much smaller than that. It shows that this species is continuing to multiply and grow on Rona. This is a foliose lichen called Pectenia plumbea. Look at the outer lobes first. They are a pale grey colour, with a darker strip along the growing edge, but see how they are covered with a pale network of fine lines. Yet there are no obviously either longitudinal or transverse features which are found in similar species. Then in the centre of the thallus you see a lot of red-brown apothecia with pale margins. Many are very small, only a fraction of a millimetre wide. This is a young thallus, and although it's already producing spore-producing structures, these have not got to their normal size yet. The largest is about 1 mm across, which is a more normal size in older thalli. Although this species has no soredia or isidia, it does sometimes produce what are described as "knob-like lobules", and you can see many of those in the centre, around the apothecia, as well. This, like other Pectenias grows only in parts of the country with a strong oceanic influence, so only in the west of Scotland, the west of Ireland and a few locations in west Wales and south-west England. I'm always excited when I find one.
June 3, 2025 at 7:37 PM
geoffrey311.bsky.social
Thank you for the tip on Saturday's #lichen. Find it in #Isle-of-Rona.

Today we stay with Saturday's birch tree, and explore some other lichens on it. Here are three foliose lichens, all with isidia.

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#lichenGBI #fungi-friends
When recording I always start with a location reference. I'm in the UK, so I use the Ordnance Survey National Grid. I just take a screen-shot of an app which uses my phone's GPS to get the location reference and the elevation. This is the lichen that drew my attention to this particular birch tree as I walked past it. After the last few posts you may recognise it. Here is a small, young thallus of Lobaria pulmonaria. It's good to see that on Rona this species is still reproducing and finding new hosts. I was surprised to see it on a birch. This Lobaria is rather dehydrated, hence the brown colour. If you look closely you can find a few isidia on it, and plenty of white scars where isidia have broken off. Isidia are little "pegs" that grow out of the thallus. They contain both fungal and algal cells, so that when they break off and are dispersed, if they end up in a suitable place, they are ready to grow into a new lichen thallus Notice the other lichens in this image. These are what we'll explore next. There's one at top right, and another at bottom right. Here's the one at top right. Here is another foliose lichen, with large lobes which have very irregular margins. Look closely [what you always have to do with lichens!] and you'll see some very fine black hairs growing from those margins. These are called cilia. One theory is that they help to maintain air-spaces between the lobes. One lobe is partly turned up, and you can see the underside. It's brown near the margin, but becomes black closer to the centre of the lobe. On the right of the photo there are some pale-coloured growths on the margins and on the upper surfaces of the lobes, and other short black cilia are growing from these growths. These growths are the isidia of this species. This is Parmotrema crinitum, and one of its distinctive marks is cilia growing out of the isidia. I haven't heard any theories about this feature! I see @sim-elliott.bsky.social‬ also posted some images of this lichen yesterday. And so to the lichen at the bottom right. Here is a very common lichen, but this one is well-established and is growing well. It is rarely found with apothecia on it, but you can see quite a number of apothecia in this photo. This is another foliose species with smaller, more narrow lobes. The younger lobes, which aren't covered with isidia, show a pattern of white, linear features, both on the margins and forming partial networks on the upper surface. These have the rather long name of pseudo-cyphellae [no hyphen; I put one in to break up the long word]. These are essentially breaks in the upper cortex, showing the white medulla, the central purely fungal part of each lobe. At first the isidia develop from these pseudo-cyphellae, but in this photo the isidia cover much of the lobes. Notice too how isidia are growing profusely from the pale (thalline) margins of the apothecia. There are a few thin black hairs to be seen on the margins of these lobes. These are probably not cilia, but rhizines on the underside. Rhizines serve to anchor the lobes to the tree they are growing on. But there may not be any real structural distinction between cilia and rhizines: just where they grow from and what they do. The apothecial discs, with a brown upper surface, produce the fungal spores which can become caught up in the atmosphere and may be transported over large distances before falling on a suitable host and developing into a new lichen. This lichen has two methods of reproducing: isidia for short-range reproduction, and spores for long-range reproduction.
June 2, 2025 at 7:26 PM
geoffrey311.bsky.social
Can you help me?
Not all #lichens are big & easy to identify like Lobarias.

Some are spectacular in other way. Here’s a thin crust I only noticed when its soralia fluoresced brightly as I checked an adjacent lichen.

What it is I don’t know. Any help will be appreciated. #Isle-of-Rona #lichenGBI
This is the bark of an old silver birch tree. There is more than one lichen here, but they are all difficult crustose ones in varying shades of grey and brown. But when the UV light from my torch fell on this part of the bark you can see how the soralia on one of the lichens stood out with a bright fluorescence. Here is the bark under ordinary daylight. Not much to see, but varying shades of grey and brown with a black line at the edge of one lichen, and some pale grey dots which are the soralia which had fluoresced so brightly. The two photos don't quite match up, but they overlap. The thallus of the lichen we're looking at was very thin and a dark grey colour. I tested it with C and K and both tests were negative. I should have tested the soralia too, but I've no record of having done so. I was trying not to get involved with difficult crusts, but that bright fluorescence caught my attention and has made me curious. Does anyone have any thoughts or ideas? Here is the tree this lichen was growing on. It was a silver birch, standing beside a track and it was well-lit from all directions. It had a fascinating mix of lichens on it: a small, young Lobaria, some young Pectenias, an Usnea, a Ramalina, a Parmotrema and others. It seems not to have been the usual acid bark of a birch which most lichens avoid.
May 31, 2025 at 7:38 PM
geoffrey311.bsky.social
There were 4 species of Lobaria in Britain, but after genetic studies some 10 years ago 3 of these have been reclassified into other genera.
All 4 former Lobaria were recorded as present on the #Isle-of-Rona in 1990, so I was keen to see if I could refind them. In the end, I found only 2. #lichenGBI
Ricasolia virens (formerly known as Lobaria virens) in a semi-dry state on a tree trunk. This was the second of the four former Lobarias I found, and it is commonly found wherever Lobaria pulmonaria is found (the first of my Lobarias, featured yesterday) Nothing can be seen of the tree trunk itself. It is completely covered with moss and lichens. On the left of the image is a large patch of R. virens in shades of pale green and brown. Its many small lobes are up to 1 cm wide. Some of these are smooth with the edges turned up a little. Older lobes are wrinkled. Lots of apothecia can be seen. Mature apothecia are up to 3 mm wide with a red-brown disc and a pale margin, and many of these are turned up at the margins. More immature apothecia are seen growing on the surface of the lobes, smaller and with thicker margins. This lichen appears to be growing over the mosses and other lichens on the tree. A green moss is trying to reassert itself, growing up between lobes of the lichen. Small podetia from a species of Cladonia are also pushing through between some of the lobes. Ricasolia virens in its fully hydrated state, unmistakeable with its bright green lobes. "Virens", the name of this species, is a Latin word meaning green. The new genus, Ricasolia, is named after Simone Ricasoli, a 19th-century Italian botanist. Notice again the apothecia, mainly on older parts of the thallus. And notice the large, loose lobes of Lobaria pulmonaria growing just to the right of the R. virens. A very dry and brown specimen of Ricasolia virens, spreading from a dead and fallen tree onto an outcrop of rock. Here the R. virens is growing over existing lichen species on the rock. The wrinkled lobes and upturned apothecia, as well as immature apothecia on newer lobes can all be seen here. This lichen may be dormant now, but as soon as it rains and the lichen becomes re-hydrated it will be bright green once more, alive and flourishing. Here are the records of lichens on Rona prior to my own visit this May. The four former Lobaria species are highlighted in yellow. I looked keenly for the other two species, Lobarina scrobiculata and Ricasolia amplissima. There was one piece of deciduous woodland which we passed on our way into the Big Harbour (Acairseid Mhòr) on Rona, which I would like to have examined. But the difficult nature of the only track, and the absence of other paths, made that too difficult for me (I've recently become somewhat disabled). My lichen expeditions had to be restricted to the two 1 km grid squares nearest to the house we stayed in. So all I can say is that although these squares contained a representative collection of habitats, I failed to find the other two species in them. Whether they still exist elsewhere on Rona I cannot say.
May 30, 2025 at 5:28 PM