PREFACE: This text provides information about common and uncommon annuals, biennials, perennials, bulbs, ornamental grasses, herbs, and hardy ferns that are adapted to most climates of the United States and Canada. The fourth edition is larger than the previous edition and I expect that a future edition will be even larger. The learning process of a plantsman is a life-long endeavor and I will continue to discover new plants in my travels. The idea for this text started developing when I was a student in a herbaceous plants course at the University of Illinois. At that time, I realized that there was no one text that included identification characteristics and the ornamental and cultural features necessary to obtain a complete understanding of the subject. This idea was further reinforced when I became an instructor of herbaceous plants at Kansas State University. I found it impossible to recommend any one book for student use because each had its advantages and disadvantages. This text provides the student, the professional, and the home gardener with illustrations and concise treatment of plant information. I have had an opportunity to travel extensively in the United States, Canada, Europe, and Great Britain. Information gained in these travels has been incorporated in this expanded fourth edition. There are over 1 20 new plant descriptions and now a total of 384 color photos. Wildflowers and herbs are two examples of plant groups where coverage has been expanded. Since the printing of the third edition of the Manual of Herbaceous Ornamental Plants, I have received many helpful suggestions of how this text could be enhanced. I am indebted to those individuals who took time to contact me with their suggestions. I have assimilated their comments and incorporated them in the fourth edition. The art work for the fourth edition was done by Lynda Chandler.