Hothfield Churchyard lichens

Ros Bennett took us on a fascinating tour of Hothfield Common and then Hothfield churchyard to search for lichens:

Aspicilia

Aspicilia calcarea. This is the lichen described as being like big white splashes of paint on rocks such as hard limestone (as in the British Lichens website) - or in this case walls and tombstones. In overall appearance it is a very white rounded splash. In detail however it is described as being a slightly bluish-white, with one or more unevenly outlined apothecia buried into areolae, with quite a distinct margin to the thallus. In this picture there are some areas of brownish stains, where there are fewer apothecia present.

The picture below of this thallus from Hothfield is much less cropped:

The Aspicilia genus is generally characterised by its largely sunken "apothecia" although they do project normally from time to time. The genus also often has a slightly cracked to distinctly areolate appearance of a generally light coloured thallus on rocks, usually (but not invariably) calcareous. The growth form is often variable, sometimes dramatically so.

There is a quite similar species of Aspicilia found fairly regularly on concrete in towns, Aspicilia contorta subsp. hoffmanniana.

Caloplaca

This is probably one of the Caloplaca species, and should I think be Caloplaca aurantia, with flattened lobes on the placodioid margins. That feature distinguishes it from another common churchyard lichen, Caloplaca flavescens, which has more convex lobes.

This species has darker apothecia, orange to dark brown as they go over. Between the older thallus and the fresh creamy orange lobes, there may appear an apparently lighter zone.

Here is a more cropped photo of the marginal lobes, emphasising the flattened lobes. The Caloplaca is fighting for space with the white crustose species.

Caloplaca teicholyta is a grey species, that looks rather "dirty" with some patches darker than others.

Here is a close-up of the "coral-like" lobules.

Haematomma

This should be Haematomma ochroleucum in both its forms, the whitish (var. porphyrium, lacking usnic acid) and the yellow-grey, var. ochroleucum, with usnic acid). The surface is quite powdery, leprose or farinose.