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Looking at lichens

This week it's time for another guest blog.


Next time you are out for a walk in your local park, stop for a moment and look closely at the trees. Within seconds of turning your attention to the bark, you are sure to spot a lichen! Clinging unassumingly to the bark in a seemingly endless array of colours & shapes, lichens are one of nature’s miracles in miniature.

As a naturalist of 20+ years, I’ve only just started to appreciate lichens and now that I’m hooked on them, I’m not sure how I’d managed to ignore them for so long! In this blog, I introduce you to the main types of lichens and encourage you to go out and have a look for yourself …

There are over 2000 different species of lichen in Britain. Although they look like one ‘thing’ they are in fact a combination of two simple organisms, a fungus and one or more algae, growing together. They grow on various substrates from wood to stone and soil, although in this blog we’ll focus on lichens on trees. Different species of lichen prefer different trees, and they also prefer different positions on trees. Lichens are present all year round so there’s really no excuse not to get out there and start looking!

Lecanora chlarotera

There are three main types of lichen but the first you’re likely to spot are the crustose lichens. You’d be forgiven for thinking someone had stuck a piece of chewing gum to the tree – the ‘crust’ lichens really cling to the bark and generally form roughly circular shapes. Here is an example of a crustose lichen, Lecanora chlarotera. Look closely and you’ll spot the little ‘jam tarts’ in the centre – these are the fruits!


Xanthoria parietina

The second type of lichens you’re likely to spot are the foliose lichens – the ‘leafy’ ones. Here is a common one, Xanthoria parietina. It’s bright yellow colouring, leafy lobes around the edge and those lemony ‘jam tarts’ in the centre make it an easy one to recognise.






Lastly, there’s the fruticose lichens. These bushy beauties are what most people imagine when they think of lichens. Here’s a common example, Usnea subfloridana.

Usnea subfloridana

The identification of lichens down to species level is complex, sometimes involving microscopes and chemical tests! We often get so hung up on ‘naming nature’ that it can start to take the enjoyment out of it. I’d really encourage you to just get out there, start looking for the three main types of lichens that I’ve described above and just appreciate them as the miniature miracles of nature that they are.


With thanks to Elaine Rainey.

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