The present edition has been entirely rewritten. While the general plan of the first edition has been followed, some changes have been made.

The number of trees included has been wholly arbitrary. All woody plants of the State which generally attain a maximum diameter of 10 cm. (4 inches) at breast high are regarded as tree forms. Alnus rugosa which so closely resembles Alnus incana, is an exception, and a description of it is given to aid in the identification of our tree form of Alnus. Also several species of CratÆgus are included which commonly do not attain tree size. The species of all CratÆgus begin to flower and fruit many years before they attain their maximum size. The genus is much in need of study, and the smaller forms are included to stimulate a study of the genus, and in order that the larger forms may be more easily and certainly identified.

The number of introduced trees has been limited to those that more or less freely escape at least in some parts of the State. The one exception is Catalpa bignonioides, which is given to help separate it from our native catalpa, both of which are now commonly planted.

Botanic Description.—The botanic descriptions have been made from specimens collected in Indiana. In most instances the material has been quite ample, and collected from all parts of the State. Technical terms have been avoided, and only when precision and accuracy were necessary have a few been used which can be found in any school dictionary. The length of the description varies in proportion to the importance and interest of the species and the number of characters necessary to separate it from other forms. The characters used are those which are the most conspicuous, and are generally with the specimen at hand. In most instances mature leaves are at hand, and these are most fully described. When leaves are discussed, only mature and normal leaves are considered. The descriptions are not drawn to include the leaf forms, and sizes of coppice shoots or seedlings. Measurements of simple leaves do not include the petiole unless mentioned.

When the term twig is used, it means the growth of the year. Branchlets and branches mean all growth except the present year. By seasons are meant the calendar seasons.

The size of trees is designated as small, medium and large. These terms are defined as follows: Small trees are those that attain a diameter of 2 dm.; medium-sized trees are those whose maximum diameter is between 2 dm. and 6 dm.; large-sized trees are those which are commonly more than 6 dm. in diameter. Diameter measurements are at 14 dm. (4¹/₂) feet above the ground, or breast high.

The common names given are those most generally used in our area. Where common names are rarely applied to our forms, the common commercial or botanical common name is given. In some instances where a tree is known by several names, one or more of which are often applied to a related species, the liberty has been taken to select a common name which should be restricted to the one species.

Botanical names are usually pronounced according to the English method of pronouncing Latin. The accented syllables have been marked as follows: the grave (\) accent to indicate the long English sound of the vowel and the acute (/) accent to show the short or otherwise modified sound.

Measurements have been given in the metric system, and in some instances the English equivalent has also been given.

The nomenclature attempted is that of the International Code. The sequence of families is that of Gray's Manual, 7th Edition.

Distribution.—The general distribution of the species is first given, which is followed by the distribution in Indiana. The general distribution has been obtained by freely consulting all the local floras and general works on botany. The Indiana distribution has been obtained for the greater part from specimens represented in the writer's herbarium and from notes in doing field work during the past 24 years. Since the first edition of the "Trees of Indiana" was published the writer has traveled over 27,000 miles in Indiana, via auto, making a special study of the flora of the State, and has visited every county and has traversed practically every township in the State. In discussing numbers in distribution it was decided to use terms already in common use, but to assign a definite meaning to each as follows: Very common means more than 25 trees to the acre; common, 5-25 trees to the acre; frequent 1-5 trees to the acre; infrequent, 1 tree to 2-10 acres; rare, 1 tree to every 11-100 acres; very rare, 1 tree to more than 100 acres; local when the distribution is circumscribed or in spots.

Where a species has the limit of its range in our area, its distribution is sometimes given at length for scientific reasons. It should be remembered that some of the older records of distribution were made by geologists or inexperienced botanists, and when such records are questioned it is done with a spirit of scientific accuracy. Some of our early authors did not distinguish between cultivated and native trees, which involves the distribution of certain species.

The habitat of many species is discussed; which suggests forestal, horticultural and ornamental possibilities. Then too, the habitat of a tree, helps to identify it. When associated trees are given, those are enumerated which are characteristic of the species throughout its range in our area and they are arranged in the order of their abundance.

A county map of the State is included which will assist in finding the range of each species. A forestal area map is also added to visualize certain habitats of the State.

The range and distribution of the species in the State has been given considerable attention to encourage investigation along this line.

Remarks.—Under this title the economic uses of the trees and their products have been given. In addition horticultural and unclassified information is included.

Illustrations.—All of the illustrations except two are photographic reproductions of specimens in the writer's herbarium. The two drawings were used in the first edition.

About 20 of the photographs were made by Paul Ulman, and the remainder by Harry F. Dietz, who has laboriously tried to obtain good reproductions from the material at hand.

Explanation of Map of Certain Forestal Areas.—In describing the distribution of certain species of trees within the State, it was found convenient to speak of certain forestal areas which are here described, and are illustrated by a map which may be found at the end of the text.

Lake Region:—The southernmost lakes in Indiana are those located in the southwestern part of Wells County; Lake Galacia about five miles northeast of Fairmount in Grant County; Lake Cicott in Cass County; and Kate's Pond about 1¹/₂ miles northwest of Independence in Warren County. Roughly estimated, all of Indiana north of a line connecting these lakes might be considered the lake area of the State. Prairie Area:—While the interior of Indiana has quite a few small areas called prairies, the real western prairie did not extend far into the State. The dividing line is very irregular, and several elongated lobes extended farther east than indicated by the map. The larger areas east of the line were the extensive prairie area of the Kankakee Valley; the northern part of Pulaski County; and parts of White and Tippecanoe Counties. "Knob" Area:—This is the hilliest part of the State and is located in the southcentral part. It is contained in the unglaciated portion of the State, and includes the "knobs" of the Knobstone, Chester and Mansfield sandstone areas of Indiana. In this area are included the scrub pine and chestnut oak, with one exception; sorrel tree and the chestnut, with two possible exceptions. The Flats:—This is a level stretch of country, here and there deeply eroded. Being level, and the soil a fine compact clay, the drainage is poor which suggested the local name "flats." The Lower Wabash Valley:—This is part of Knox, Gibson and Posey Counties which is usually inundated each year by the Wabash River.

Acknowledgments.—The character and qualities of the wood have for the greater part been taken from the works of Britton and Brown, Hough, and Sargent, to whom indebtedness is acknowledged.

The SalicaceÆ, except the genus Populus was written by C. R. Ball, of the Bureau of Plant Industry, Washington, D. C. The MalaceÆ was contributed by W. W. Eggleston, also of the Bureau of Plant Industry, Washington, D. C. These authors were asked to make their part conform to the general plan of the book. Mr. Ball and Mr. Eggleston are recognized authorities on the respective parts they have written and users of this book will appreciate the value of having these difficult parts written by our best authorities. The author wishes to gratefully acknowledge this great favor.

The most grateful acknowledgement is given to Prof. Stanley Coulter, Dean, School Science, Purdue University, who has read all of the manuscript and made valuable suggestions, corrections and criticisms.

I wish to acknowledge the assistance of Stella M. Deam, my wife, in field and clerical work.

I wish to thank the Department of Conservation for the opportunity of doing this work.