(In this volume the remaining - British species, not described in greater detail in Vols. II-V, are arranged according to their principal habitat. Some of the species might be included in more than one section, and, as the distribution of some is limited and the habitats are restricted, the choice of habitat in such cases is arbitrary. For convenience the large genera, such as Rubus, Rosa, Hieracium, Salix, and Carex, are very largely described under some one section in which a large number of the species would be rightly included. As far as possible all the British species are included, but in the case of the large number of "aliens" only the better-known ones are described. Recently denned segregates, as far as possible, are also dealt with.)