Southern Marsh Orchids

Southern Marsh Orchids

Thursday, 9 January 2014

Distinctive Lichen

With a bit of reasonably dry weather today, I took the opportunity to pay a visit to the old limestone quarries below Morlais quarries, just north of Merthyr Tydfil. I was there a couple of weeks ago, but that time I was with Mike Hogan, visiting a cave to count hibernating moths. This time I wanted to check on a distinctive and relatively uncommon, foliose lichen called Peltigera leucophlebia. I first found it growing there several years ago and as it is the only site I know for it in

Glamorgan, I like to keep an eye on it. It is quite a large, leafy lichen; bright green, with pale undersides to the thallus and those tell-tale blackish, raised cephalodia. P. leucophlebia is only to be found in calcareous situations and there is a very similar Peltigera: P. britannica, which is only found in acid situations in uplands. The cephalodia of P. britannica can be easily scratched off, leaving a pale scar, but those of P. leucophlebia cannot be easily removed.
Although the quarries are quite extensive, this lichen only grows in parts of the upper tiers of the middle and upper branches of the quarries, usually amongst slightly taller vegetation on the areas that are less grazed by sheep. I was encouraged to find it to be even more abundant on some areas I haven't checked before.

While there I also came across this local crustose lichen: Gyalecta jenensis, which has distinctive orange centred apothecia. It is often found in growing along cracks and fissures in the vertical faces of the limestone and commonly colonises mosses already growing there.

Gyalecta jenensis, probably on what was formerly a small clump of

Caught in the act of colonising a moss

This rust fungus was quite abundant on the Salad Burnett up there. When I get the chance, I'll drag the microscope out and identify it.

1 comment:

  1. The Peltigera lichens are amazing. We don't have leucophlebia in the abandoned quarries in Rhoose, but we do have one of the darker coloured species, (probably canina or didactyla) although unlike yours, it seems to have really suffered badly recently. I guess that may be the hot dry weather last summer as it as in an area with virtually no soil, so it is either very wet or very dry.

    You probably know this already, but others may not, many Peltigera have a cyanobacteria as the photosynthetic symbiont which gives them the ability to fix nitrogen.

    I will keep an eye out for G jenensis here!