A recurring theme will be the use of medieval plants available before 1500. These were essentially plants that had a practical domestic or economic use. Many of these were native wild flowers; others were early introductions from the Mediterranean region.
Churchyards can be havens for wildlife: they support trees; wildflowers can thrive in the lawn; lichens, mosses and ferns on the headstones and church walls. Plants, in turn, support insect life including bees and butterflies and these in turn attract birds and bats.
Norfolk was once rich in wildflower meadows but traditional management has been replaced by new methods involving the use of inorganic fertilisers and pesticides. It is estimated that since 1945 we have lost 98% of English wildflower meadows. Churchyards are often remnants of an earlier time and can be vital to the survival of wildflowers.
The Norwich churchyards are chemical free and relatively undisturbed, which makes them potentially attractive to wildlife. They could offer valuable refuges for all of the above plants.