An introduction to Shetland lichen

I started this blog with a working title of ‘Diving into lichen’ but, on reflection, I realised this was a wildly inappropriate oversimplification. I’ve barely dipped my toe into the lichen shallows. And, if we’re to extend that metaphor a little further, it’s just enough to know that those shallows have dangerous rip-tides and fall away, precipitously, like a continental shelf-edge mere feet from the certainty of dry land.

Does this make lichen sound daunting? Well, they are… but at the same time, what a beautiful challenge they represent. Some years ago, aware that my Shetland home was festooned with lichen, from the shaggy greybeards that sprouted from old drystone walls, to the saffron crusts that smothered clifftop rocks and, tenaciously, the very roof of my old croft house, I did what I always do when I want to learn more about something – I bought a book.

If I’m honest, Shetland Lichens set me back a few pounds from the Shetland Times Bookshop, but also set my lichen-hunting back by a few years. I’d hoped for a field-guide that would help me to readily identify whatever I happened to find. What I got was a comprehensive monograph listing the lichens that had been found to date throughout Shetland, but with precious little information about how to set about actually identifying anything.

Life then got in the way of further progress. Researching and writing Orchid Summer ate into what precious little free time I had available to me. Then the cycle repeated itself with The Glitter in the Green… (Due to be published this year in the USA in April, and in the UK in June). Nonetheless, this past January, with lockdown keeping me at home, and spoilt by an uncharacteristically fine and prolonged spell of weather for Shetland at this time of year, I determined to try to get to grips with the lichens I could find close to home.

And this time I was, if not fully prepared, then certainly a little more confident than hitherto. I’d found Frank Dobson’s brilliant Lichens – An Illustrated Guide to the British and Irish Species and, online, I’d found a helpful cadre of lichenologists on Twitter who kindly held my hand as I made my first baby steps and wild stabs in the dark identifying what I stumbling across on Whalsay’s shores, walls, moors and outbuildings. Two of them, Brian Eversham and Mark Powell, I owe particular thanks to for their patience and assistance. A new world, one that had been under my nose all these years, was opening up…

It all began with a couple of grey splats on the rocks at the shore – some with glistening black apoethecia (these are lichen fruiting bodies), and others with regular, sculptural disc-shaped apothecia, with neat rims around them like tiny jam tarts. These weren’t too hard to identify for myself – Tephromela atra and Ochrolechia parella respectively, both common lichens in these coastal parts.

A walk on the hill behind the house uncovered more unusual treasures – Sphaerophorus fragilis with delicate branches of filigree the colour of old ivory, and my first Cladonia species – the red matchsticks of Cladonia floerkeana and C. bellidiflora, and the green pixie cups of what may, or may not, be C. chlorophaea – the latter are needing further investigation. This, I was finding, is part of the joy of lichen-hunting – solving some identities isn’t straightforward, but nor should that be off-putting – it’s like solving a knotty riddle or crossword puzzle clue. There’s some satisfaction in a hard-earned resolution.

Nearby were some foliose lichens amongst the moss that blankets much of the hill – the wrinkled and somehow ancient ‘leaves’ of Peltigera membranacea, and the smoother, chestnut-apothecia bearing P. hymenina. The latter seems to be previously unrecorded on Whalsay – as were several more of the lichens I was finding. In the kirkyard were Whalsay’s first records of Physcia tenella, a fabulous grey lichen with corrugated, exuberant black apothecia, and the gorse-yellow branches of Xanthoria candelaria.

Another Xanthoria, X. parietina, covers rocks at the shore in a rich mustard crust. On the shaded walls of an old stone sheep dip I found it growing in more glaucous tones. Those sheep dips also yielded the gorgeous, subtle Caloplaca crenularia – a grey lichen with conker-coloured apothecia, easily overlooked but, on closer examination, a stunner.

Other Caloplaca lichens were more obvious – the yellow species found on the shore were unmissable, particularly the black and orange C. microthallina and deep orange C. marina. Amongst them was a prize – not a particularly rare lichen, but one that’s surely overlooked in Shetland – C. maritima, a lichen of lemon and lime tones that’s hitherto only recorded from Fair Isle.

Some of these lichens have English names but, while I’m usually a great fan of colourful and evocative language like that found amongst the English species names of moths and hummingbirds, in the case of lichens I’m sticking to the scientific names. That’s because the world of lichen has a language all of its own – a lichen lexicon. From apothecia to Zwackhiomyces (the latter a fungus found on Xanthoria parietina), I’m loving diving into a sea of new words.

I’ve come to realise that lichens are everywhere here – and that there are a wealth of discoveries to be made that help to add to our understanding of their distribution here in the islands. It’s like the scales have fallen from my eyes in the first few weeks of this year, and I can’t wait to see what else I can find. There’s an entirely new world out there on my doorstep waiting to be explored, and my voyage of discovery is only just beginning.