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,
Burrington Combe as a Site of Special Scientific Interest in 1952. The calcareous grasslands support a diverse flora which includes Salad burnet ("Sanguisorba minor"), Knapweed ("Centaurea scabiosa" and "Centaurea nigra"), Rock-rose ("Helianthemum nummularium") and Wild thyme ("Thymus praecox"). On the higher, more acidic, slopes Goldenrod ("Solidago virgaurea"), Wood sage ("Teucrium scorodonia") and Common Bent ("Agrostis capillaris") can be found. There are also scrub plants including Hawthorn ("Crataegus monogyna"), Mountain ash ("Sorbus aucuparia"), gorse ("Ulex europaeus") and Elder ("Sambucus nigra"). Several of the caves support bat populations. Geologically it is recognised as a fluvial karst feature which partly intersects a buried and filled