Ginny B's picture

Lepraria sp.?

The first lichen photo I put on iSpot was identified for me as probably Lepraria incana. There is a lot of this in the various woods where I walk. I know the colour can vary quite a bit, but can it also appear the rather yellowish, chalky, very pale green that I see on the bark of many of the Scots pines (Pinus sylvestris), or is this something else, like algae? With a hand lens I can see that it looks like very fine granules.



AlanS's picture

Having a life v Lepraria

Hi Ginny,

I think the answer is to not worry too much and look at something else.

The problem is that Lepraria species are highly reduced, asexual lichens with little structure that helps us humans to differentiate species. (This appears not to be a concern for the Lepraria.)

In the past, it was an easy matter to lump most of them as "Lepraria incana", but DNA studies have told us two things:
a) they do, for the most part, form a natural group of species;
b) there are a LOT of species but many poorly defined morphologically.

I think at times that DNA taxonomists tend to lose the plot, recognising minor taxa at specific rank (this has been termed "taxonomic inflation"), without thinking more broadly about species concepts, and there are certain assumptions to the "cladistic" species concept that basically should not be assumed.

However, inconvenient though it is, it does seem that the numerous Lepraria species are well founded and are ecologically distinct, even if it takes a laboratory to identify them.

The only answer is to study the account by Alan Orange in The Lichens of Great Britain and Ireland, which lists 22 species. It does include a key that can be used when thin-layer chromatography is not available, but it still requires carefully applied chemical tests and examination of hyphal structure (if any) under the granules. With practice, it would seem that some entities can become recognisable (but note that I use the term "morphospecies" on my website). Those included in Dobson are a good selection of those that do present a chance of identification.

Colour is important, but unfortunately is variable in each species and with much overlap. Degree of dryness or dampness of the lichen, degree of exposure, general health of the lichen (including fungal attack), all affect the colour.

To actually answer your question, it is possible to make a reasonable field guess at Lepraria incana, at least in East Scotland where you operate, provided that it is distinctly blue-grey, is thin, and has no underlying white medulla - i.e it is simply a layer of granules. It must be on acid tree bark (e.g. birch, pine, sessile oak). It is more variable than this, but then we have more overlap with other species. Any orange-brown patches should react purplish-red with KOH (but the rest of the thallus is K-). Unlike some similar species (e.g. L. jackii), it is bluish white under appropriate UV light.

So that's one of the easier species done, now ....

Well you should get to know L. lobificans - spongy appearance, minutely projecting filaments from the granules (photos on my website), common on oak and other trees. L. membranacea is common on highland oaks and is white and somewhat lobed (will add it to my website when the mood takes me, umbricola and ecorticata also in the queue). See my website for L. rigidula that should find in your area, often overgrowing Parmela sulcata.

And after that, I think there are two alternative actions to take:
a) be Alan Orange
b) take up something else, anything else, as it is bound to be more rewarding.


Ginny B's picture

Not worried, just intrigued.

Hello Alan,

That was a most interesting read. I hadn’t realised quite how complex the Lepraria species was to identify. Thank you so much for taking the time and trouble to explain it to me. I just wish I had started to learn about lichens when I was much younger.

I have spent many hours on your website attempting identification of the various lichens I’ve come across, not always successfully I’m afraid – the darned things seem to look so different in different conditions! But, having just looked at your photos of L. lobificans and L. rigidula, they look familiar so maybe I’ve already met them without knowing. I’ll have to go back now and have another look!

Sorry, but I can’t do either of your final suggestions!
a) No matter how hard I try I will never be an Alan Orange much as I’d like to have his knowledge.
b) It’s too late, I seem to have become hooked by lichens and can’t stop looking both at and for them. So, although there will be times I will tear at my hair in frustration at not being able to identify them, I suspect I shall most likely be looking at them for a long time to come.

Thanks again Alan.


jhn7's picture


I too enjoyed reading Alan's explanation so thank you for asking the question! I'm afraid I'm only at the level of marvelling at looking at lichens and trying to identify the common ones but I'm full of admiration for those who have such incredible knowledge. Thank you to Alan for your detailed and, even for me, understandable reply.

Certificate in Contemporary Science (Open)