Crawley, M., 2005
The Flora of Berkshire
An immense piece of work detailing what is known of the higher plant flora (and listing the mycota) of vice county 22.
In addition, it presents a distillation of the author's many years' experience of botany (and snippets of entomology) so is useful outside the vice-county for a more hands-on and personal view of plant identification than given by most floras, as well as background information on ecology.
The hints for some groups (eg Quercus petraea, robur and their hybrid) are more useful than those published elsewhere.