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,
Sorbus aucuparia Pliocene age. Fruit of "S. aucuparia" were used in the past to lure and catch birds. To humans, the fruit are bitter, astringent, laxative, diuretic, cholagogue, prevent scurvy, and the parasorbic acid irritates the gastric mucosa. Pharmacist Mannfried Pahlow wrote that he doubted the toxicity of the fruit but advised against consuming large amounts. The fruit contain sorbitol, which can be used as a sugar substitute by diabetics, but its production is no longer relevant. "Sorbus aucuparia" fruits have been used in the traditional Austrian medicine internally (as tea, syrup, jelly or liqueur) for treatment of disorders of the respiratory