=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 1-1/2 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.