A number of photographs and drawings have been introduced throughout this volume. These photographs are illustrative of various group ideas covering uses of plants. Words, however carefully selected, often cannot be a literal interpretation of an idea, whereas a photograph immediately conveys the definite idea which cannot be reproduced in words. These illustrations have been selected, so far as possible, to illustrate the main features which justify the making of an individual group for reference purposes. It is hoped that they may for that reason prove to be of great value.
Theoretically, a treatise on any subject should be so simplified that to the average reader the method of using it is self-evident. However, a few suggestions covering the methods of consulting the information in this volume may not be amiss. The Table of Contents, which is a complete compilation of all the general information in this volume, is arranged with many larger and more important headings to include the many minor headings. It is here that the reader can easily find reference to lists of plants which are valuable for specific uses by exactly the inverse process that he can find from the Index a reference to the different purposes for which an individual plant may be used. To the reader who is seeking to find a list of plants which can be used for a specific purpose, first, the Table of Contents and the List of Illustrations are of direct and primary value. To the reader who is seeking to find for what specific uses any plant may be adapted, secondly, the Index to pages and groups of plants is of greatest importance. To the reader who wishes to go farther into the subject of plant study, as covered by various phases of landscape work, thirdly, the Bibliography is the one reference which will be of value. The complete glossary containing a complete list of definitions covering terms frequently used by landscape architects is of real value in defining such terms.
The criticism may be raised by some who consult a volume of this kind that in reality no definite line can be drawn between the uses of some plants for one purpose or for another purpose. This is admittedly a fact. It will be quite evident from a short study of the Index that many plants frequently have a distinct and definite value as adapted to different purposes.
While the range of material covered by the lists is sufficient to meet the requirements of the average property holder, the lists may be supplemented by additional and unusual varieties which, if selected, should be given unusual care. The information in this book has been compiled to cover the range of material which is adapted for use generally throughout the following portions of the United States: The North Atlantic States, the Great Lakes Region, the Central States as far west as the Missouri River and as far south as Arkansas. No lists have been compiled for the Great Plains and the Rocky Mountain States, but special lists have been compiled for the Atlantic Coastal Plain from Virginia to Mississippi; also for the Peninsula of Florida and for the region within a radius of one hundred and fifty miles from the Twin Cities. For the Pacific Coast, lists have been prepared for the Oregon-Washington Coastal Plain. It should be borne in mind that plants which develop one type of growth in a northern climate will develop another type of growth, because of the longer growing season, in a southern climate.