Rhos Blaen Carrog is a Site of Special Scientific Interest in Ceredigion, west Wales, due to its population of Wavy St. John's Wort (Hypericum undulatum), an extremely rare variety of St. John's Wort.http://www.ccw.gov.uk/idoc.ashx?docid=5d7fb388-fea5-44b0-b28d-34e116fc92bb&version=-1
References
See also List of Sites of Special Scientific Interest in Ceredigion