CONTENTS 



PART I. 



INTRODUCTORY. 



Page. 



The North American Forest 13 



Forests of Pennsylvania 13 



The Forests and Forestry 16 



Forestry in Pennsylvania , 17 



The Structure of the Forest 19 



The Establishment of the Forest 21 



The Development of the Forest ; 23 



The Protection of the Forest 26 



The Value of Forests, 28 



The Value of Trees 29 



Deciduous and Evergreen Trees 30 



The Age of Trees 31 



The Form and Structure of Trees 32 



1. F\)rm 32 



2 . Bark 34 



3. Twigs 36 



4. Buds 38 



5. Leaves 40 



6 . Leaf-scars and Bundle-scars 43 



7 . Flowers , 44 



8. Fruit 46 



9 . Wood 49 



PART II. 



MANUAL OF PENNSYLVANIA TREES. 



Identification of Species 55 



Names of Trees 55 



Explanation of Terms and Headings 56 



How to Identify the Species and Use the Keys 58 



General Key to the Families 63 



Tabulation of Genera and Species 65 



Description of the Families. Genera, and Species 67 



Glossary 220 



Index, 225 



(11) 



