To anyone who loves the wild flowers of Great Britain and Ireland, there are some places that beckon time and again, such as The Lizard in Cornwall and Ben Lawers in Perthshire, Scotland. However, Upper Teesdale in England’s County Durham needs to be included among these jewels of our botanical heritage. This locality, which is within sight of the highest point of the Pennines, has an outstanding and special flora that has been shaped by its altitude, land-use patterns and diverse geology. Many of the plants found in Upper Teesdale are rare and localized, while others are more common and widespread, but together they form the botanically unique Teesdale Assemblage. For this reason, Upper Teesdale is a hotspot for avid gardeners and botanists. It is also a scenically beautiful area, located within easy reach of the industrial heartlands of the north-east, and is much visited by walkers and tourists. This book offers visitors unique insights about this area and its botanical riches.