More around St David's

Almost any patch of clay ground appears to hold Ephemerum crassinervium ssp. sessile 

It's hard to believe that Ephemerum crassinervium ssp. sessile is Nationally Scarce, or that Bosanquet (2010) only listed two Pembrokeshire sites for it. Perhaps it's having a good year, but there are dozens of patches of it in any open clay ground in grassland, heath and pond edge on sites around St David's. It's often accompanied by Ephemerum stoloniferum, and sometimes closely admixed, but it can be reliably picked out by the longer, narrower perichaetel leaves even before a hand-lens reveals a nerve.

Another species apparently gaining ground is the Nationally Rare Acaulon mediterraneum, with a new site - the fourth in the county - found on St David's Airfield. This is the first that's not on an exposed headland, and in the same open clay patches as the Ephemerum.  In contrast, the Acaulon quickly colonising the new heathland creation field nearby was muticum.

After finding Cephaloziella integerrima new to the St David's area on the airfield heaths last week, checking the gemmae on various samples turned up another patch on the northern side of the runway. This one was in similar open clay / subsoil and also shaded by a gorse bush (a feature noted on a couple of Cornish records too). I also found a third population on a pile of clay-rich subsoil in Middle Mill Quarry near Solva.

Cephaloziella integerrima location, Waun Llechell

Acaulon mediterraneum spores

On the Bug Farm at Harglodd-isaf, a streamside boulder in rough pasture held a patch of Grimmia laevigata, like the Acaulon mediterraneum only otherwise known in the county from exposed coastal slopes. A good find here was a non-fruiting Physcomitrium in a recently created winter-wet scrape, which appears to be Physcomitrium sphaericum under the microscope. I would have expected the first county record of this to come from the reservoir at Llys y Fran, but it illustrates how good these things are at dispersing. 

Grimmia laevigata

apparent Physcomitrium sphaericum and habitat