Vm META.SPERMAE OF THE MINNESOTA VALLEY. 



Climate 576 



Tables of precipitation 576, 577 



Table of temperature 577 



Phaenological observations 578 



Geological history of the Minnesota valley 578 



Bibliography 581 



Relationships of the Metaspermic flora of the Minnesota 



VALLEY 582 



Statement of the problems 582 



The dynamic inter-relations of plants 582 



General features of plant distribution 584 



The general factors in floral differences 587 



Natural vegetation regions of the earth 588 



Grisebach 588 



Engler 588 



Drude 590 



General position of the Minnesota valley as a botanical 



district 591 



Greater compositeness of the Northern Realm 591 



Pressures and tensi07is 594 



General considerations of equatorial pressure 594 



Movement of tensions 595 



Fluctuation of tensions 596 



Influence of equatorial pressure on habitat 597 



Secondary longitudinal tensions 598 



Minor tensions 599 



General division of the world into botanical realms 600 



Outline of metaspermic history in the northern hemisphere 600 



Emergence of metaspermic forms 600 



Character of the Cretaceous flora 602 



The Tertiary flora 603 



The post-Tertiary movement 604 



Results of the epoch of glaciation 606 



Conditions of the present 610 



Summary 610 



Bibliography 612 



Statistics of Metaspermic plants of the Minnesota vAr.LKV 613 



Value of statistics 613 



Point of view of statistical compilation 614 



Points of statistical investigation 615 



/. Examination of families represented in th:. ,\[innesota valley — 624 



A. Table illustrating distinctive range of families 618 



//. Examination of genera represented in the Minnesota valley . . . 624 



B. Table illustrating distinctive range of genera. 624 



C. Table illustrating continental development of genera — 643 

 ///. Examination of species represented in the Minnesota valley 653 



D. Table illustrating general continental range of Minne- 

 sota Metaspermic species 654 



E. List of species and varieties of extra-continental rang*; . . 724 



F. Table illustrating range by families and species 736 



