Cwm Celyn revisited - 27 years on

In July 1991 I went on my first ever BSBI walk - led by Trevor Evans to Cwm Celyn in NW VC35.  I have fond memories of the day, as I saw 10s of new plants from Equisetum sylvaticum and Carex laevigata to Carum verticillatum and Mimulus moschatus.  The cwm has been a big, bad blank on my bryophyte coverage map until today, because it was clearly a site deserving proper attention rather than a quick visit.  6 hours' searching racked up 105 species, including 2 new for VC35, so it was worth the wait!

 

I started in the adjacent tetrad, SO10Z, where the Rising Sun Industrial Estate added some 'grots' to the >50 upland species recorded a few years ago from further west in the square.  Surprise highlight was large Aneura sp. in marshy secondary woodland in the middle of the industrial estate.  Things started slowly in SO20E, although Leptodictyum riparium was present by the reservoir and Hyocomium armoricum was abundant by a rocky stream.

As I carried on upwards through a clearfelled conifer plantation I found the first new county record - Pohlia camptotrachela on a damp forestry track.  Unfortunately I didn't realised it was 'needed' and replanted the tuft I had checked, so that one awaits vouching.  A Pennant Sandstone quarry supported abundant Racomitrium lanuginosum and R. fasciculare, as well as a few tufts of Ptychomitrium polyphyllum.

 

 

After a quick march up to the head of the cwm, at 440m altitude, I set about exploring an area of flushes and a stream gully around SO209097-SO210098.  Polytrichum alpinum grew on the base of a stone wall, alongside Hyocomium armoricum, whilst the second new county record of the day came in the form of frequent Entosthodon attenuatus along the stream.  It seems rather apt that this western moss should turn up close to Monmouthshire's main site for the western plant Carum verticillatum.  A gorgeous patch of Bryum alpinum on a rock in the stream was unusual for VC35 as well.

 

The stream was fed by a mire in which 10 species of Sphagnum were present, including S. cuspidatum, S. papillosum and S. tenellum.  One spring held large patches of Dicranella palustris and Scorpidium revolvens, as well as Warnstorfia exannulata and Aulacomnium palustre.  The final surprise of the day was an 8x1m strip of Ranunculus omiophyllus - Montia fontana Rill (NVC M35), which has few if any previous records from south Wales.