10 April 2011
North-facing, Old Red Sandstone cirques in the Brecon Beacons are home to some fantastic plants like Purple Saxifrage (Saxifraga oppositifolia). This circumpolar arctic-montane species is a pre-historic footprint in South Wales, which is its most southern location in Britain. It has probably survived there since early post glacial times when it was a much more widespread member of a periglacial tundra flora like that found in Greenland today (where this species is a familiar component of the flora). Today it finds refuge on these cold Breconshire scarps along with other northern or montane species. Purple Saxifrage is also found in Snowdonia, Northern England, Ireland and Scotland, but its presence in South Wales is quite special. It is quite common on high mountains in the Alps where it often grows with Yellow Whitlow-grass (Draba azoides), which also finds refuge in our region (i.e. on south Gower cliffs - see Barry Stewart’s posting from last month). In the photograph, the little fern to the left is Green Spleenwort (Asplenium viride), which is a circumpolar boreal-montane species.