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 which is a hybrid with "Sorbus aria". The main pests for "S. aucuparia" are the apple fruit moth "Argyresthia conjugella" and the mountain-ash sawfly "Hoplocampa alpina". The rust fungus "Gymnosporangium cornutum" produces leaf galls. The leaves are not palatable to insects, but are used by insect larvae, including by the moth "Venusia cambrica", the case-bearer moth "Coleophora anatipennella", and leaf miners of the genus "Stigmella". The snail "Helix aspersa" feeds on the leaves. The plant can suffer from fire blight. Fossils of "Sorbus aucuparia" have been described from the fossil flora of Kızılcahamam district in Turkey, which is of early