Saturday, 18 February 2017

Cwm Marydd - the best of Brechfa

Less than 10 minutes' drive from Cwnc y Llwyn is the steep-sided valley of Cwm Marydd (SN5031).  It doesn't look like much on OS maps or aerial photos, but very steep sides, rock outcrops, a series of cascades, relatively old Oak & Ash, and even a mine adit (not marked on any map I've seen) make it a perfect site for bryophytes.  The bryophyte species list stands at 120, and includes Tritomaria exsecta at its only recorded site in VC44, Cephalozia catenulata, Plagiochila exigua, P. punctata, P. spinulosa, Jubula hutchinsiae and Platyhypnidium alopecuroides.  I have visited on 6 occasions before, and spent an hour there this afternoon to stretch my legs during Half Term.

Highlight was locating two trees with Plagiochila exigua alongside a waterfall at SN50383202 and SN50363199: finally getting GPS readings for this, the only known population in Brechfa Forest.  Alongside both were patches of a toothier Plagiochila with scarcely decurrent leaves that I assume is P. punctata, although its non-deciduous leaves and brown colour make me a little suspicious and I need to investigate further [I did and it still looked odd, but I'm certain it's P. punctata, with the non-papillose cuticle ruling out the far-fetched Macaronesian P. stricta].  A lot of staring at Lejeuneaceae failed to reveal anything notable, which was a surprise.

Plagiochila exigua
Interesting Plagiochila punctata with slightly decurrent leaf bases, a brown colouration like P. bifaria, and non-deciduous leaves

Two nice lichens were also present: the pink-fruited Mycobilimbia pilularis (spores checked today) was on an old Ash alongside P. exigua, and the tiny Graphina pauciloculata grew with G. ruiziana on a Hazel (microscope checking needed).  Three patches of a large lichen in the canopy of the Ash need a revisit with a telescope...

1 comment:

  1. There are some quality species amongst that assemblage, including 2 or 3 I've still yet to catch up with