Lichens – those strangely coloured crustyhairymushy organisms on trees or rocks. What are they and what are they for?
I want to know, but where do I begin?
This is a path I’ve started on many times over the years, perhaps getting as far as Wikipedia or even pulling out one of my old ID books and a hand lens. I never get far.
Lichens are mystery wrapped inside an enigma, the more you try to understand them the harder it gets.
But perhaps I’ve been coming at this all wrong.
Perhaps in our modern world of genetic testing and constantly changing taxonomies it’s time to stand back and grasp the basics, learn a few common names and stop leaving lichens to the experts. These things are fascinating so take down the barriers and come in for a closer look. Who knows, it could be the beginning of a beautiful friendship.
This guide is not designed to get you identifying lichen with certainty, but rather to provide a bit of an idea of what you may be looking at, common names vary and can be shared by different species!
I recommend googling as you go, and you’ll know your Beards from your Oak moss in no time.
So what am I looking at?
Lichens are symbiotic – they are made up of a fungi which provide the structure, and algae which do the photosynthesis. They reproduce by producing spores, or vegetatively by bits dropping off and growing elsewhere. Current research suggests that yeast is also involved… Lichen is not a single organism, but rather a community. Think coral but very different.
Lichens are grouped like plants, in genera and species and are classified by the fungal partner.
Learning to recognise lichens species can be daunting, however so is any form of plant ID for the uninitiated, so just as you learn your bulbs from your roses, let’s start with shape.
Is it bushy? (Fructicose)
These are the most obvious, big and bushy, attached at the base. Cladonia are a little different -these have long spikes or cups poking up, occasionally brightly tipped.
Is it leafy? (Foliose)
These can be wavy or flat, and are not entirely stuck down. They don’t have a clear base and occasionally have small hairs which attach to the tree or mosses.
Is it crusty or powdery? (Crustiose)
These can have raised bumps, powdery bits or coloured rings but are firmly attached to a surface.
Ready for more?
Next let’s try separating out some genera so we can put a name to things. Don’t worry we’ll keep it simple, and don’t forget to Google!
Bushy lichens are a good place to start as they’re easily recognisable. Remember their main feature is a single connection at the base – think tree.
Hair Lichen (Usnea spp.)
Identified by their round stems, can be thick or fine, long and stringy or bushy.
Strap Lichen (Ramalina spp.)
These have flat stems which are the same colour all over and fork unevenly.
Soldier Lichen (Cladonia spp.)
Not really bushy but certainly photogenic – these upright match sticks have a bright red tip.
Pixie Cups (Cladonia spp.)
Again not bushy… These lichens are like tiny fairy goblets.
Leafy lichens are far more varied and a bit trickier to describe, however a few are common enough that you can have a stab at them. Remember, leafy and usually flat or partially stuck down.
Oak Moss (Evernia spp.)
These are half way between bushy and leafy, can be hard to tell. The undersides are lighter and wider than strap lichen and branches fork evenly.
Green Shield (Flavoparmelia)
If you see a large patch of light green lichen with wrinkly leaves and powdery surface it’s probably green shield.
Yellow scale (Xanthoria)
Bright yellow and a bit leafy – not crusty. More than likely it’s a Yellow scale.
Heather rags (Hypogymnia)
A small grey leafy lichen with a brown underside, the edges are lobed and wibbly and often become powdery.
Crusty Lichens can be daunting; however some common ones stand out. These are generally just a crusty layer or coloured marking.
Bitter Wart (Pertusaria)
A green-white lichen with white warty bumps. A very bitter taste.
Firedot lichen (Candelaria)
Bright yellow or orangey and crusty – probably a Firedot lichen.
Script Lichen (Graphis)
Silvery patches on bark with wavy black lines a bit like old writing.
Rim Lichen (Lecanora)
These have dark raised disks with a clear rim around the edge.
12 Down 1688 to go!
So there we have it, 12 lichens to start you off – so get out there and look for some!
Oh and take a camera, a bit of practice and the odd filter can give fantastic results.
Explore Further
If you’d like to explore from the comfort of your chair then why not try:
Nearly 800 lichens photographed and categorised and relatively easy to understand.
http://www.britishlichens.co.uk/pictureindexcomplete.html
Join the flourishing community of British lichenologists ask questions and keep up to date with lichen events across the country.
https://www.facebook.com/BLSlichensF/