LICHENS
Welcome to the Lichens of North Wales
If you’ve made it here, you’re either already hooked on lichens… or you’re about to be.
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Lichens are everywhere in North Wales. They grow on ancient oak bark in the damp woodlands of Eryri, cling to limestone walls in Conwy, sprawl across mountain boulders in Gwynedd and quietly decorate churchyards and hedgerows in Denbighshire.
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Most people walk past them every day without noticing. But once you start looking, you realise they are one of the most fascinating and diverse groups of organisms in our landscape.
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This section of the website is where I share the lichens I’ve found and photographed across North Wales — from the obvious leafy species to the tiny crusts that need a hand lens (and sometimes a microscope) to appreciate properly.
Why North Wales is Special for Lichens
North Wales is one of the most exciting regions in Britain for anyone interested in lichens. Its mix of climate, geology, altitude, and long-standing habitats creates a patchwork of environments that support an extraordinary diversity of species. From ancient oakwoods in Eryri to windswept mountain crags in the Ogwen Valley, and from limestone pavements in Conwy to coastal cliffs and dunes, there are lichens waiting in every corner.
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The Atlantic influence is a big part of this. Moist, mild air, frequent rainfall, and generally clean, oceanic conditions allow species that are rare elsewhere in the UK to thrive here. Many woodland lichens, for example, need humid, stable microclimates, and the western woodlands of North Wales provide exactly that. You’ll find species like Lobaria pulmonaria, the Tree Lungwort, clinging to old oak trunks, or the rare Pseudocyphellaria crocata, a bright green leafy lichen that thrives in the damp understory of ancient woodlands. These are the kinds of lichens that tell a story about long ecological continuity and low pollution — they only survive where the habitat has been relatively undisturbed for decades, if not centuries.
Geology
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The geology of the region adds another layer of diversity. Siliceous rocks in upland areas provide ideal conditions for umbilicate species such as Lasallia pustulata, known as Rock Tripe, and various Umbilicaria species, which cling to exposed boulders and withstand wind, frost, and the harsh sun of the high peaks. Limestone areas support calcicolous crusts and foliose species, while lowland gravestones, stone walls, and man-made structures provide niches for species adapted to slightly altered or urban habitats. Coastal areas have their own specialists too, from salt-tolerant black lichens like Verrucaria maura that thrive on tidal rocks, to colourful orange crusts of Caloplaca on exposed cliffs.
Rare Species
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Many of the lichens here are specialists, some found only in a handful of sites in the UK. The uplands even host species more usually associated with Scottish mountains, highlighting the biogeographical importance of the region. Some are slow-growing, fragile, and easily overlooked, while others are large, striking, and perfect for photography. Recording them is more than just a hobby: it contributes to understanding local biodiversity, helps track environmental changes, and provides essential information for conservation.
The Tarn Lecanora, Lecanora achariana, is one of the most specialised and localised lichens in Britain. In North Wales it survives in only a handful of upland locations, most notably around high mountain lakes in Eryri. Its Welsh populations are of national importance because the species is classed as Critically Endangered in Britain and has disappeared from several historical sites.​
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What makes Tarn Lecanora so special is the narrowness of its ecological niche. It occupies that very precise band between land and water – too high and it dries excessively, too low and it drowns. Because that zone is so sensitive to change, the lichen is highly vulnerable. Alterations to water levels, such as raising a lake for reservoir purposes or modifying river flow for hydro schemes, can permanently remove the habitat it depends on. Changes in water chemistry through acidification or nutrient enrichment also pose risks. Even subtle shifts in hydrology can mean that suitable rocks are either no longer wetted often enough or are submerged for too long.
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In North Wales its continued presence is an indicator of relatively intact upland hydrological systems. It represents a relic of clean, naturally fluctuating mountain waters that were once more widespread. Finding it is a reminder that some of our upland lakes still function in a largely natural way, but it also underlines how fragile those systems are. Conservation of Tarn Lecanora is therefore inseparable from careful management of upland water levels and the protection of water quality in Eryri’s high tarns.
Observing lichens in North Wales teaches patience and attention to detail. The same species can look very different depending on moisture, light, and season. Returning to the same site under different conditions often reveals surprises — a dull grey foliose lichen can swell into rich green after a rain, or a crustose patch can reveal tiny fruiting bodies previously invisible. Paying attention to microhabitats, from shaded northern faces of rocks to sunlit coastal boulders, and noting the types of trees or stone, gives clues to identification.
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In short, North Wales is a living lichen laboratory. Its combination of climate, clean air, varied geology, and long-standing habitats means that whether you’re photographing Rock Tripe on a high boulder, spotting rare leafy species in an ancient oakwood, or simply noticing a tiny crust on a church wall, the region has endless opportunities for discovery. Lichens here are everywhere once you start looking — and each one tells its own story about the landscape.