Hanging Around

 Fencepost of the Week #254

 

 

Gigha Woodland Lichens

Lichen list from a visit to Southern Gigha on 8th December 2025

in roughly chronological order

-Leim Farm:
Physconia distorta - https://www.inaturalist.org/observations/329966449
Physcia tenella
Physcia adscendens - https://www.inaturalist.org/observations/330941598
Physcia leptalea? - https://www.inaturalist.org/observations/329966986
Ramalina farinacea
Ramalina fraxinea
Ramalina calicaris
Xanthoria parietina

-Into the mature trees:
Parmotrema perlatum
Anisomeridium sp? - https://www.inaturalist.org/observations/330943560
Peltigera hymenina
Normandina pulchella - https://www.inaturalist.org/observations/330941515
Coenogonium luteum - https://www.inaturalist.org/observations/330941517
Punctelia reddenda - https://www.inaturalist.org/observations/329969734
Flavoparmelia caperata
Melanelixia glabratula
Opegrapha vulgata - https://www.inaturalist.org/observations/330941036
Enterographa sp. (probably E. crassa) - https://www.inaturalist.org/observations/329970533
Pyrenula macrospora - https://www.inaturalist.org/observations/329970742
________
-Achamore, by the car park
Lobaria pulmonaria
Sticta limbata - https://www.inaturalist.org/observations/329973340
Parmotrema crinitum - https://www.inaturalist.org/observations/329973435
Usnea with bright red stems - suggestive of U. rubicunda, but it was probably decomposing Usnea cornuta s. lat. - https://www.inaturalist.org/observations/329974367
________
After lunch: 
- on stone wall
Peltigera praetextata
Peltigera membranacia
Lichenomphalia ericetorum - https://www.inaturalist.org/observations/329981229
- in boggy, newly planted woods
Sticta limbata
Sticta fuliginosa s. lat. (probably S. ciliata) - https://www.inaturalist.org/observations/329981661
Parmotrema perlatum
Parmotrema crinitum
Hypotrachyna laevigata
Lobaria pulmonaria
Lobarina scrobiculata
_______
-Shoreline, waiting for ferry
Scytinium gelatinosum 
Polychidium muscicola

Mouldering in a Gloomy Spot

 Fencepost of the Week #253

 

 

 

 

Roll-up

 Fencepost of the Week #252

 This entire fence has been pulled out of the ground and rolled up. It's still providing fertile surfaces for some nice lichens and mosses, though.

 

Grizzled and Cracked

 Fencepost of the Week #251

 

 

Cavernous Crater at Dusk

 Fencepost of the Week #250

 

 

Ricasolia virens - Cyanomorph, Chloromorph and Photosymbiodeme

Some lichenised fungi are capable of associating with both cyanobacteria and algae as photosynthetic partners. In some cases the appearance of the lichen changes very dramatically depending on which photobiont is present.

Ricasolia virens - cyanomorph

For example, here is Ricasolia virens - a small, bushy, cushion-forming jelly lichen. A cyanobacterium is the photobiont here.

But... This is also Ricasolia virens - a large, strikingly green, foliose lichen. This one has an alga as the photobiont:

Ricasolia virens - chloromorph

You can call the cyanobacterium containing lichen a cyanomorph and the alga containing lichen a chloromorph. 

Sometimes you will find a lichen with both photobionts on the same thallus - this can be called a photosymbiodeme. Here is a Ricasolia virens photosymbiodeme:

Ricasolia virens - photosymbiodeme

Related phenomena occur with Sticta canariensis and Ricasolia amplissima.

Sticta canariensis - photosymbiodeme

Ricasolia amplissima - photosymbiodeme

A slight complication: the word cephalodium can also be used to describe a lichen with algae and cyanobacteria both present, but it only allows for cases where the cyanobacteria are kept in small, subsidiary structures within or budding off of a primary chloromorphic thallus.

You can read much more about Ricasolia virens and its forms in this 2016 paper: 
The cyanomorph of Ricasolia virens comb. nov. (Lobariaceae, lichenized Ascomycetes)
By
Tønsberg, Blom, Goffinet, Holtan-Hartwig & Lindblom 
https://doi.org/10.5962/p.386096