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,
× Sorbaronia mitschurinii × Sorbaronia mitschurinii × "Sorbaronia mitschurinii, also known as Sorbaronia mitschurinii", is a domesticated species that was known until recently under the name "Aronia mitschurinii". It has been considered to be a group of cultivars of "Aronia melanocarpa", common ones including 'Viking' and 'Nero'. Genetic testing indicates it is likely a hybrid between "A. melanocarpa" and "Sorbus aucuparia" (mountain ash) that apparently originated in cultivation. It has been suggested that "Sorbaronia mitschurinii" is the product of Russian pomologist Ivan Vladimirovich Michurin's early 20th century experiments in wide hybridizations. This species is more robust than wild populations of "Aronia melanocarpa"; the