Lichens are not single organisms like a robin or daffodil, but stable communities involving a fungus and an alga (or cyanobacteria, ‘blue green alga’). Recent research suggests there are bacteria and yeasts too. The fungus provides ‘structure’; the alga makes sugars (food). Lichens provide texture on trees, rocks and walls. They are beautiful, fascinating and enigmatic, and found almost everywhere.
Looking at Lichens
Few lichens have English ‘common names’: most are known by their scientific name. Most are small and hard to identify: a hand lens (10x) helps to see the features. Lichenologists use chemical reactions and microscopes to tell them apart. For most of us, it is enough to admire them and identify them to their family. Lichens can be seen all year round, though are perhaps best observed when the trees are bare and the weather has been wet.
Lichens Tell Stories
Different lichens thrive in different places: tree age, bark texture, rock type, light and water availability, bark chemistry (and more) affect what grows where. Lichens can’t run away or close their pores so are vulnerable to pollution. Coal-burning badly affected many species, though a few thrived under acid rain! Some species have rebounded since the clean air acts, but nitrogen pollution from agriculture and vehicles is a big concern. Lichens can also tell us about the history of woodland management: tree-felling affects lichens! Slow-growing species may take centuries to recolonise; others can return in just a few years.
Want to learn more about our land and the species you can find there? Look out for our other guides! www.friendsofthelakedistrict.org.uk/property-guides
The first stage is to look at how it is growing. Some are: Leafy (below left) – where a lobe has a top and bottom that are different.
Fruity (above right) – where pieces hang down and there is no obvious top or bottom side.
The fungal partner may produce sexual spores from fruiting bodies such as apothecia (these may look like ‘jam tarts’ or ‘wine gums’.)
Crustose – where it is very hard to remove the lichen from what it is growing on.
The next stage is to look at how it is reproducing:
Or the lichen may reproduce asexually by producing Soredia (below left) – a powder containing both alga and fungus, or Isidia (below right) – little peg-like outgrowths.
Some seem to reproduce just by having bits fall off them!
Lichen Species found in Friends of the Lake District’s Woodlands
If you would like to know more about lichens you could look at the British Lichen Society website: https://britishlichensociety.org.uk or for more information about Cumbria’s lichens: https://cumbrialichensbryophytes.org.uk.
Normandina pulchella
Sometimes called ‘elf ears’ this has bounced back after the fall in sulphur dioxide pollution. It is usually found on mossy, less acidic-barked trees.
Rhizocarpon geographicum
‘The map lichen’, found commonly on acidic rocks (including walls) in sunny spots.
Peltigera species
Known as dog lichens, these can grow relatively quickly among mosses on trees and rocks, or even your lawn! There are several different kinds.
Xanthoria parietina
‘The sunburst lichen’ will grow on almost anything. It thrives with lots of light and nitrogen pollution: it is very common on ash twigs. The yellow colour is a chemical that acts as a sunscreen: in winter or in shadier spots it is more blue-grey. Our woodlands are wonderful to explore. Each feels different thanks to variations in climate, age, history of management and pollution. The lichens growing in them vary greatly. This guide introduces some of those to be found.
Cladonia species
There are a bewildering variety of Cladonia lichens: those with cups and red fruiting bodies are very attractive to beginners. They can, however, be very hard to tell apart.
Graphis species
These crustose lichens are found on trees. The apothecia (fruiting bodies) are elongated like mysterious writing.
Parmelia saxatilis
Cumbria’s most recorded lichen, it grows on acid rocks and acid-barked trees such as birch. The pegs are isidia, an asexual reproduction feature.
Pertusaria pertusa
‘The pepperpot lichen’ is a crustose species found on older trees. The holes are how the spores leave the fruiting bodies.
Thelotrema lepadinum
‘The barnacle lichen’, usually found in ancient woodlands on older trees with smoother bark.
Usnea species
These fruity lichens are indicative of clean air and, often, acid bark.
About Friends of the Lake District
Established in 1934, Friends of the Lake District is a membership-based charity committed to looking after the landscapes of the Lake District and Cumbria.
Scan here to become a member today. Join us and over 6,000 people who are passionate about this magnificent place.
Friends of the Lake District’s land is open to the public and for all to enjoy! We own land from Threlkeld in the north, to Kendal in the south, and from Eskdale in the West, to Asby near Orton in the east. This is a mix of farmland, common land and woodlands.
For more information on our land, how to join us and help to maintain these beautiful Cumbrian landscapes or volunteering opportunities please get in touch, or sign up to our email newsletter.
Friends of the Lake District, Murley Moss, Oxenholme Road, Kendal, LA9 7SS
