The scaly male ferns are fascinating plants that many people have difficulty in identifying. In his pictorial guide, the late Ken Trewren illustrated and explained the main distinguishing features of many of the recognisable forms covering the species, subspecies, and hybrids that appear in Stace's 2010 New Flora of the British Isles along with some that have not yet been formally named. A great strength of Some Taxa within the Dryopteris affinis complex lies in the detailed photographs of the key features used for recognising these ferns. Ken Trewren painstakingly put together this remarkable set of images over years of study of the Dryopteris affinis complex.