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,
North Fork Mountain pine barren in the Central Appalachians. Other rocky summits, including the summit of Pike Knob, are blanketed by red pine ("Pinus resinosa") forests, here at their southernmost natural occurrences. The Monongahela National Forest has designated of old growth red pine forest on the mountain as the North Fork Mountain Red Pine Botanical Area. Another unusual vegetation type on North Fork Mountain is an elfin forest dominated by yellow birch ("Betula alleghaniensis"), mountain ash ("Sorbus americana"), and mountain holly. The oak-and-pine vegetation of North Fork Mountain contrasts strongly with the more diverse vegetation of the nearby mountains just west of the