The Cornish hedge is unique as a man-made wildlife refuge, with everything needed for the full cycle of the life it supports – earth, stone, crevices damp and dry, shelter, decaying matter and a huge variety of plant life from microscopic fungi to forest trees. Aiding this amazing variation of species and habitat is the mild Cornish climate, which favours activity all the year round.
The hedges provide habitats which may have shrunk elsewhere, including the characteristics of flower-meadows, woodlands, scrub, field margins, heathland, wetland, rocky outcrops and sea cliffs. Their long continuous history means they are often species-linked to the original pre-farming landscape. Examples of self-sustaining Cornish hedge plants include elements of original woodland eg dog's mercury, wood sorrel, and bluebell, and of original heathland eg gorse, heather and tormentil. The hedge stones host a scree population of lichens, mosses and other life suited to the dryness of the hedge, while in the damper hedges most of our ferns luxuriate.
The Cornish hedge produces a seasonal succession of different species rooted between the same stones. Primroses, violets and other spring flowers can only grow on the hedgebank because the tall summer flowers shade and protect them from drought. Campion, bluebells, foxgloves, scabious, betony, yarrow and many others follow in their turn all summer, with berrying plants such as bryony in autumn, many flowering throughout winter. When seed is allowed to ripen and fall, this rich succession is renewed naturally every year. In 1971, nearly two hundred flowering species were counted in just one mile of an ordinary roadside hedge. An estimated ten thousand species
of insects can be supported by the floral and habitat diversity in Cornwall's hedges. This brings mammals, birds and reptiles to forage and to hide their homes and nests in the greenery and stony crevices.