Meeting date: 12 November 2016
(Leader: Keith Palmer)
South-East England Lichen Group
Contact: Dr Tim Rayner – email@example.com
There were just the three of us at Rusper. It rained heavily in the hour and a half up to the start time and drizzle persisted under cloudy skies throughout the meeting. Everything therefore was very wet with no opportunity for drying out! 103 species had been recorded on two visits in the early 1990s. The total for last Saturday fell well short of that. Even taking into account the damp conditions rendering many species difficult to determine there would appear to have been major changes in the lichen flora in the intervening twenty-two years. Some of this may well be due to shading by tree growth especially by conifers and the impression of a damp, shaded and rather gloomy churchyard was difficult to shake off!
Even so there were a few species which had not previously been recorded. Chief amongst these was Caloplaca variabilis which I would regard as easily the find of the day. This is a common enough species in the Midlands but is surprisingly scarce in the south-east. I know of it from only one other churchyard in Sussex, Chailey near Lewes. There was a healthy colony of Placynthium nigrum on a low slab on the better-lit road side of the church. Caloplaca crenularia was common on one granite headstone, a somewhat unusual habitat; previously it had been recorded here on flagstones.
Perhaps the most successful lichen in the yard was Haematomma ochroleucum var. porphyrium which was abundant and which in some cases, the thalli fused together, covered whole sides of headstones. However in many spots it had been well grazed. Lecidella scabra was richly fertile on one memorial. Psilolechia leprosa was noted on copper run-off both on the church wall and on a stone monument resembling an urn. Solenopsora candicans was re-found, healthy on a single headstone though no fertile thalli were detected. Verrucaria muralis was still present and Caloplaca dichroa was new by virtue of this species being un-named at the time of the last visit. Lignum was an important habitat here but again the old boundary fence and the various benches were not obviously rich in species, being significantly shaded, Cladonia macilenta, Cladonia coniocraea (not previously known from here) and a good deal of Flavoparmelia caperata. There were no species recorded from trees and even on the last visit corticolous species were marginal.
Losses appeared considerable. Where on earth have all the Physcias gone, or the Xanthorias? A full range of these lichens was present in the 1990s including Physcia dubia on granite headstones. Not one Physcia of any description could be found today and only a few fragments of Xanthoria parietina found growing on moss cushions. Other apparent losses (and this must be treated with some caution owing to the conditions on the day) included Aspicilia subcircinata, Caloplaca flavovirescens, Hypocenomyce scalaris, Hypogymnia physodes, Lecanora pannonica, L. soralifera, Parmelia saxatilis, Punctelia subrudecta, Platismatia glauca and Pertusaria pertusa on rock.
It would be good to visit the site again on a fine dry day in summer to confirm or otherwise some of these serious losses.