CONTENTS. 



Introduction 235 



General features of the flora 236 



Life 7.ones 238 



Transition Zone 239 



Canadian Zone 241 



Hudsonian Zone 245 



Arctic-Alpine Zone 247 



Scope and plan of the flora 249 



Earlier botanical exploration 251 



Acknowledgments 253 



Bibliography 253 



Systematic treatment . 255 



Key to the families 255 



Annotated catalogue of species . 263 



Index IX 



