Rhossili Down

Tortula wilsonii (tbc) was the highlight of a wander around the n.w. section of Rhossili Down yesterday. It was growing as a few discrete, but dense patches totaling c.3 sqcm on soil ledges on a Brownstones Formation outcrop, Gower's oldest (Silurian) rocks SS41729038. Immediate soil associates included Sedum anglicum, Thymus polytrichus, Hypnum cupressiforme var. resupinatum, Trichostomum brachydontium, Pseudephemerum nitidum, Ceratodon purpureum, Cladonia sp. & Lepraria sp.

The same ledges held a few patches of Campylopus fragilis, at what is only the second site for Glamorgan.

Another Glamorgan first was Philonotis arnellii (tbc), which occurred as thinly scattered shoots on the steep mossy bank below Gorse and Bramble scrub, adjacent to the footpath at the base of the hill SS41649051. This is the site where I previously found Fissidens curvatus, which I failed to refind yesterday. Associates included Fissidens bryoides, Amblystegium serpens, Mnium hornum, Kindbergia praelonga, Richardia chamaedryfolia, Lophocolea bidentata & Weissia perssonii.

A small outcrop at the same location held Pterogonium gracile with Riccia subbifurca on the overlying thin soil crust. Anther colony of the Riccia was found higher up the hill on an ant hill.

All in all, it was a good afternoon, with a bonus ring Ouzel to boot (though not the views enjoyed by Charles & Hilary and Cwm Ivy the week before). The walk off the hill, following the stream below three spring heads, which held Sphagnum denticulatum & subnitens, plus Bryum alpinum & Sarmentypnum exannulatum, added some useful tetrad records that included Hookeria lucens, Plagiothecium denticulatum, Scpania undulata, Pellia neesiana, Campylium stellatum & Oxyrrhynchium speciosum.

Cwm Clydach (CCS)

It's been a while since I've indulged in any serious recreational bryology, so today it was good to get out and enjoy a 500m search of a tributary of the Lower Clydach River (centred at SN677066). Although this was an attractive little wooded valley, it was generally rather open and lacked any waterfalls or crags. Nevertheless a few noteworthy species were recorded including Odontoschisma denudatum (5 different logs scattered evenly along my walk - 4th vc tetrad), Barbilophozia attenuata (4th vcr), Dicranodontium denudatum (4th vcr), plus a potential candidate for Philonotis arnellii (below, top two images), though my sample although distinct, seemed bigger than I might have expected arnellii to be. An examination of the older leaves shows the cells in the outer 1/3 of the leaf has distal mammillae, but I need a more focused re-examination of my specimen to consider other perhaps more likely possibilities.

Below, Odontoschisma denudatum locations (also on log in top photo): 

Philonotis arnellii

The books make out that Philonotis arnellii is a featureless moss that is easily confused with the very much commoner P. fontana.  That is true to an extent, but it's one of those species that is really quite distinctive when you see the real thing: when you think you've found it, you've got P. fontana and it's only real P. arnellii when you know you've got something different.  Most colonies I have found are on earthy ledges alongside rivers, perhaps flooded once every few years, but I've also seen it in the uplands on ledges and occasionally on flushed lane banks (perhaps like Barry's recent one).  I haven't found convincing material on forestry tracks, where juvenile P. fontana is frequent and confusing. 

Look for relatively dense patches of consistently very small shoots with very narrow leaves, expect there to be abundant deciduous branchlets (there usually are) and look for fertile buds (with even longer, narrower leaves) with a lens.  A microscope is needed to check the cell mamillae: look at mature leaves on the lower, brown sections of the stem.  Here are four photos from a large colony near Brechfa in central Carms.