2 METASPERMAE OF THE MINNESOTA VALLEY. 



list there will be found reference to many of the lower plants, 

 but the number here determined can hardly represent more 

 than a small fraction of all which certainly exist within the 

 limits of Minnesota. 



During the three years of 1889, 1890 and 1891, the collection 

 of data in this comparatively unexplored region has been 

 diligently prosecuted by the Botanical Department of the 

 University of Minnesota, and the information thus obtained 

 has become the property of the survey. It is intended at some 

 time in the future, barring unforeseen contingencies, to present 

 as complete a list as possible of the fungi and algae of the 

 state. While this reconnoisance has been in progress much 

 labor has been expended upon the enlargement of our knowl- 

 edge of those plant-groups which have already commanded, 

 from their greater prominence, the attention of students of the 

 Minnesota flora. Owing to the changes in nomenclature and 

 the never-finished revision-work which modifies our conception 

 of genera and species as well as of the larger divisions, and in 

 the light of constantly advancing scientific knowledge, there is 

 brought near to us the necessity of re-examining somewhat of 

 the botanical work already done. By such examination it alone 

 becomes possible to present the most modern aspect of such a 

 study as is, under the law, directed towards the vegetable 

 products of Minnesota. 



In the present volume a mass of revisional and considerable 

 new material bearing upon the plants of Minnesota has been 

 collected. For a proper limitation of the work within bounds 

 a natural group of plants — the higher seed-plants, or metas- 

 permae — has been selected, and these plants have been consid- 

 ered with reference to a limited, but natural portion of the total 

 area of the state. In this way new facts are conveniently 

 grouped and the old facts are brought into a somewhat different 

 angle of vision. 



The importance of studying a natural area. It is not com- 

 monly the custom of those who compile local floras to select dis- 

 tricts limited by nature rather than by man, as the area for inves- 

 tigation. It is far more usual for some political district to be 

 chosen, such as, for example, a group of states, a single state, 

 a county, a town or a region within a circle drawn with arbitrary 

 radius around some central city, lake or valley. In a list of 

 local floras published in North America (3), Dr. N. L. Britton 

 enumerates 791 titles of works that have been published since 



(;(). Britton: A list of IStalc and Local Floras. Oontr. Col. College Herb. (18!)0.) 



