This definitive flora provides detailed accounts of the native species, naturalised species, frequent garden escapes and casuals found in the British Isles, including some newly described ones. Full keys and descriptions enable the user to name all plants occurring in the wild and some ornamental trees and shrubs. For the first time, accounts of all the large apomictic genera are included. Each species entry begins with the accepted Latin name, synonyms and English name. A detailed description follows, with the flowering period and chromosome number. Separate descriptions are provided for infraspecific taxa and many hybrids. The status, ecology and distribution (including worldwide distribution) of the taxa are also given. Black and white line drawings illustrate an extensive glossary and illuminate the diagnostic features in several genera. Volume 1 includes historical and taxonomic introductions to the whole project and a combined index of accepted names and selected synonyms of families and genera in all five volumes. Publication dates are as follows: Volume 1 - 12 April 2018; Volume 2 - 18 December 2014; Volume 3 - 12 February 2009; Volume 4 - 06 April 2006; Volume 5 - 10 April 1997.