The Flower Expert: The world's best-selling book on flowers by Dr. D. G. Hessayon. Millenium Edition, 1999. Expert Books. Manual básico sobre jardinería escrito en INGLÉS. English The Flower Expert is one of the books in the Expert series written by the world's best-selling gardening author. Quite simply, the world's best-selling book on flowers. Inside you will find many hundreds of different examples of annuals, perennials, alpines and bulbs.