Backstone Bank and Baal Hill Woods one side valley, there is a small population of small-leaved lime, "Tilia cordata", which occurs here close to its northern limit and at an unusually high altitude. On base-rich soils, the woodland typically consists of ash, "Fraxinus excelsior", and wych elm, "Ulmus glabra", over an understorey of hazel, "Corylus avellana", and bird cherry, "Prunus padus", and a rich ground flora that includes lady-fern, "Athyrium filix-femina", male fern, "Dryopteris filix-mas", and hard shield-fern, "Polystichum aculeatum". On more acid soils, sessile oak, "Quercus petraea", and birch, "Betula sp.", are dominant. The under-storey, of hazel, holly, "Ilex aquifolium", rowan, "Sorbus aucuparia", and hawthorn,
Mountain Ash, Rhondda Cynon Taf the Aberdare branch of the Merthyr Line of the Transport for Wales rail network. Further to Mountain Ash railway station, the village of Fernhill and Penrhiwceiber is also served by the Aberdare line. Bus services are operated by Stagecoach in South Wales. An early British railway line had developed from the industrial development within the South Wales Valleys, which with its core centred around Mountain Ash became known as the Mountain Ash Railway (MAR). Having developed from an early tramway, it became in the 1970s the last core of steam locomotive operations in the UK. Developed by Powell Duffryn as