The parish of St Oswald's lies North West of Chester at the base of the Wirral and covers the five townships of Mollington, Lea-by-Backford, Backford, Caughall and Chorlton-by-Backford.
Geologically, it is based in an area consisting mainly of boulder clay but with considerable Triassic sandstone outcrops. The more recent history has modified the natural landscape.
Originally, the two rivers, the Dee and the Mersey, prior to the canalisation of the Dee, converged within the parish at high tides. Following the canalisation of the Dee the Shropshire Union Canal was subsequently built along the route of the low-lying ground through the parish. The Cheshire landscape is also dotted with many small ponds. Backford Brook is one of the few fresh water streams in the area.
Most of the larger fields are farmed intensively, principally for milk production, but with the cereal crops, maize and grass being taken for silage. Spraying does cause a reduction of species in these areas.
Within the boundaries of the parish there are several, relatively undisturbed areas where plants can flourish without damage by man. These include periphery of the motorway, the railway embankment, areas of the canal banks, a number of undisturbed small woods, and a number of bridle paths.
As a result of the range of habitats available for species to flourish is very varied. The species listed are to be found at exposed sites such as roadside verges but also the quieter locations such as hedgerows, bridle paths, field ponds, canal banks, motorway banks and by Backford Brook.