This is part of our Good Practice Guidance for Habitats and Flora, produced by Richard Jefferson, Dominic Price, Iain Diack, Steve Coates and Andy Mclay.
Reference: Poland, J. & Clement, E.J. (2009) The Vegetative Key to the British Flora: a New Approach to Plant Identification. Botanical Society of the British Isles, London, UK.
This book is now out of print.