Thread by @obfuscans3

A few more parmelioids (Parmelia and related genera) from my walk today.
Can you detect the yellowish tinge in this Flavoparmelia caperata (pure grey Hypotrachyna at top right for comparison).

Flavoparmelia caperata in lower half, Hypotrachyna revoluta above. Again the subtle difference in colour which can only be accurately judged when the lichens are dry (they all become greener and rather similar in colour when damp/wet).

Here we have the two British Flavoparmelia species side by side. Similar colour. F. caperata (left) tends to be more robust, soredia coarser, produced in pustular soralia. If in doubt a simple chemical test will distinguish them.

Flavoparmelia soredians (left) compared again with F. caperata (right).

Hypotrachyna revoluta (left), Flavoparmelia caperata (right), these from shade so the yellowish tinge perhaps not so distinct on the latter (and the interior greenish due to slight overgrowth of free-living algae).

Flavoparmelia caperata (left), Hypotrachyna revoluta (right) with a few tufts of Evernia prunastri between them.

Parmotrema perlatum, a big floppy-lobed thing with fine soredia on upturned edges of internal lobes. Check for cilia (eyelashes) on margins of lobes if in doubt.

Hypotrachyna revoluta (left) can appear similar to Parmotrema perlatum (right) due to both having apices of erect lobes covered in fine soredia. When getting to grips with them, a drop of bleach on the medulla can help distinguish.

Hypotrachyna afrorevoluta (left) is a relatively difficult split from H. revoluta (right) and it would be unwise to name them without closer inspection (or considerable experience).

Hypotrachyna revoluta (left) vs. H. afrorevoluta (right)

Extreme 3d effect of H. revoluta, erect lobes covered in fine soredia. However this is a mixed colony and I am suspicious of the robust lobe towards right side, might be a stray lobe of H. afrorevoluta.

When it is as frilly as this, Punctelia jeckeri is fairly distinctive, but spot tests and close attention to fine details are recommended when learning the different parmelioids.

This is a common situation, at least five parmelioid spp. growing together. Clockwise (sort of) starting from right side - H. revoluta, P. subrudecta, H. afrorevoluta, P. jeckeri, Parmelia sulcata.