Llanelli Naturalists Newsletter - March 2003 - No 69
Ian Morgan

The rather pessimistic forecast of rain put off some members, whilst later, more were discouraged by the climbing of the Pennant Sandstone bluffs alongside the Afon Morlais below Craig Fawr!  The purpose of the meeting was to show members the Tunbridge Filmy-Fern Hymenophyllum tunbridgense (first found here by Sam Bosanquet in December 2001) and the Hay-scented Buckler-fern Dryopteris aemula.  The party descended an oblique path down to the Morlais (= ‘Mawr lais’ i.e. ‘big stream’) but the rock outcrop at the base of this path yielded little of interest, though a pair of grey wagtails were utilising it for nesting.

The party then continued downstream on the right (west) bank, with another riverside outcrop visible, just after a bend in the river.  Several participants declined to inspect this outcrop due to the difficult nature of the terrain, in spite of the leader’s reassurances!  Those who did were rewarded with both H. tunbridgense and D. aemula; the former forming dark green patches on the rock outcrops and the latter characteristically ‘crispy’ in appearance.  These ferns, like many of the specialist bryophytes (mosses and liverworts) that occupy this cwm depend on the humid, virtually frost-free conditions provided by the stream and the tree-sheltered deeply incised valley.

The remnants of the party then continued, following the same bank-side and zig-zagged upwards, through the corner of a conifer plantation until a more substantial cliff face was viewed which was under a canopy of oak Quercus sp. woodland with a ground flora dominated by Bilberry Vaccinium myrtilus .  Some of the party then decided that this was too much and opted for an easier route.  Christopher Cottingham, Barney Gill and Richard Pryce followed the leader and traversed this cliff, seeing more Hymenophyllum and the rather rare moss Bazzania trilobata (both near the top) en route.  Having crossed this cliff we then descended on another pathway to its southern end where, in a humid recess, another plant of Dryopteris aemula was seen.  This remnant group of ‘survivors’ again tackled the cliff, walking/climbing at an angle to reach the northern top corner; again we saw another plant of aemula before rejoining the main party at the little car park near Craig Fawr.

We are grateful to Greg Wilkinson for his encouragement and allowing access to his land, and also to Sam Bosanquet for drawing further attention to the interest of this site. N.B. Photographs of Tunbridge Filmy-fern appeared in Llanelli Naturalists Newsletter 68 and Hay-scented Buckler-fern in Llanelli Naturalists Newsletter 67.

Reference

Bosanquet, S.D.S. (2002).  Cwm Clydach, Cydweli SSSI, bryophyte survey. CCW internal report, Haverfordwest. [includes survey data and comparisons of several south-east Carmarthenshire cwms].