One of the great things about dry stone walls is their value as wildlife habitat. When a wall gets older it can accumulate all manner of plants and lichens. Dry stone walls are good for this as gaps can get filled with soil particularly where the wall is retaining an earth bank where moisture can flow through. The flora is quite different depending on the geology of the stone from which the wall is being built. In this sandstone wall in Yorkshire you can see Woundwort, Sweet Woodruff, Foxglove and Teasel are all able to grow in and around the wall itself.