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 alnifolia fruit (persistent in other whitebeams), but genetic evidence places it close to "Sorbus aria". It is occasionally grown as an ornamental tree in northern Europe, primarily for its autumn colour. The cultivar 'Skyline' has been selected for its fastigiate growth. Sorbus alnifolia Sorbus alnifolia (syn. "Aria alnifolia"), also called alder-leafed whitebeam, Korean whitebeam, or Korean mountain ash, , is a species of whitebeam native to eastern Asia in eastern and northern China, Taiwan, Korea and Japan. "Sorbus alnifolia" is a medium-sized deciduous tree growing to 10–20 m tall with a trunk up to 30 cm diameter and grey bark; the