Another book I studied when undertaking my second assignment was Fantastic Flowers by Clay Perry, Kyle Cathie Limited, London, 2000.
The book has photographs of about 75 different flowers presented alphabetically from Acanthus to Zantedeschia (calla lily).
There are many different approaches to lighting, set up and vantage point so it is a great way to study how someone has approached all the possible ways of photographing flowers.
Personally I think his close-ups work best (or that may just be my prejudices about what makes a good flower photograph) although all his images are of the highest quality.
Some of his photographs can be seen at the langtons international gallery website.
It is interesting to compare the photos in this book with those of the same flower taken by Mapplethorpe. To me the Mapplethorpe images are somehow more intense and more sensuous.