Common Lichens on the Heathland near Round Hill (Esher Common)

Just three members met on 12th September to survey the woods, conifers and the heath vegetation near Round Hill for lichens. The area is most suitable for terricolous species, i.e. lichens, mostly foliose, found directly on the soil or growing on exposed roots of heather or trees. From the car park, opposite Arbrook Common, we walked through dense woodland to get to the heath area at the top, which runs parallel to the A3. Very few epiphytic lichens like deep shade, so we found only two of the commonest species in the Commons: Dimerella pineti and Lepraria incana. The species can be distinguished by the colour of the thallus, being smooth and greenish in the former, but bluish grey and of powdery appearance in the latter. Lepraria species are always sterile, but D. pineti is also recognised by its fruit bodies: small beige discs. Despite oak being one of the best substrata for epiphytic lichens in Esher, there were no foliose species until we reached the edge of the heath where the lower branches of a young oak had about eight macrolichens: Ramalina farinacea (a young specimen without soredia), Parmelia sulcata (with reticulate soredia), Punctelia subrudecta (a parmelioid rosette with punctiform soredia), Melanelia subaurifera (the most widely spread olivey-brown parmelia), Flavoparmelia caperata (a member of the yellow parmelias), Parmotrema chinense (also known in the past as Parmelia perlata), Candellariella xanthostigma (or mustard lichen), and our first Cladonia: C. macilenta (a narrow cup species).

After that we had to look down to find our objective, and we really had to apply ourselves since the soil was very dry, making it difficult to see the lichens. Nevertheless, we recognised, in a mossy area, Cladonia fimbriata (the commonest of the 'pyxie cup' cladonias in this heathland) and Cladonia coniocraea (similar to C. macilenta when sterile, but separated from it by the lack of K reaction). To find the lichens, we had to stick to the paths and other areas where the heather had been removed or was not so vigorous, which raised some questions on how to manage the habitat so that it is also good for lichens. In this area we also found Cladonia furcata, C. polydactila - a red-fruited species with smooth sorediate scyphes that look like fingers, and Peltigera hymenina - a species associated with a cyanobacterial photobiont. Other species of Peltigera have been mentioned from the Commons, but the records need confirming. Peltigera hymenina was known in the past as P. lactucifolia, perhaps because the lettuce-like appearance of the thallus (see picture below).

The footbridge crossing over the A3 had distinct orange rosettes of Xanthoria (most likely X. calcicola by the rugose aspect of the mid-thallus) and greenish-grey ones of Lecanora muralis. Both species are very common on man-made substrata throughout the borough. Two-and-a-half hours later our final survey was on the wettest part of the heath, dominated by gorse and some sedges, just on the left hand side of the small pond after the footbridge. Here we found the Peltigera in great abundance, together with dry crusts of cyanobacteria, and our last three new Cladonia species: C. rangiformis (a look-alike reindeer moss), C. bellidiflora (red-fruited, but with small squamules covering the scyphes) and C. cervicornis (forming distinctive cushions of whitish squamules). To test our taxonomic abilities C. furcata was growing alongside C. rangiformis. We separated both on the basis of the sympodial scyphal growth of the first, whereas the reindeer moss look-alike develops by dichotomous branching.

Our final interesting lichen, although sterile, was Baeomyces rufus, usually found on sandy wet embankments, and only known so far from this area of the Commons and Oxshott Heath, by the sand pit area. Just to finish this account, I would like to say thank you to Dick Alder for teaching us the many non-lichenised fungi we also encountered.

BEGOŅA AGUIRRE-HUDSON