The Manual of the Botany of the Northern United States / Including the District East of the Mississippi and North of North Carolina and Tennessee

MANUAL OF THE BOTANY OF THE NORTHERN UNITED STATES,
INCLUDING THE DISTRICT EAST OF THE MISSISSIPPI AND NORTH OF NORTH CAROLINA AND TENNESSEE.
By ASA GRAY, LATE FISHER PROFESSOR OF NATURAL HISTORY IN HARVARD UNIVERSITY.
Sixth Edition.
REVISED AND EXTENDED WESTWARD TO THE 100th MERIDIAN, BY SERENO WATSON, CURATOR OF THE GRAY HERBARIUM, HARVARD UNIVERSITY, AND JOHN M. COULTER, PROFESSOR OF BOTANY IN WABASH COLLEGE,
ASSISTED BY SPECIALISTS IN CERTAIN GROUPS .
WITH TWENTY-FIVE PLATES, ILLUSTRATING THE SEDGES, GRASSES, FERNS, ETC.
IVISON, BLAKEMAN, AND COMPANY, PUBLISHERS , NEW YORK AND CHICAGO. 1890.
Copyright, 1889 , By the President and Fellows of Harvard College.

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.