The opening of Preface
The first edition of Gray's Manual was published in 1848. It was to a great extent rewritten and its range extended in 1856, and it was again largely rewritten in 1867. The great advances that have since been made in systematic botany and in the knowledge of our flora have for several years past made another revision desirable, which Dr. Gray before his death was purposing to undertake.
The present editors, acting to the best of their ability in his stead, have endeavored throughout to follow his methods and views. The original plan, so long retained by Dr. Gray and so generally approved, has been closely adhered to, the characters and descriptions of the last edition have been left essentially unchanged so far as possible, and in the numerous alterations and additions that have been considered necessary or advisable, his conclusions and principles have governed in every matter of importance, so far as they could be known. The effort especially has been to maintain that high standard of excellence which has always made the Manual an authority among botanists.