THE GEOGRAPHICAL DISTRIBUTION OF NORTH 
DAKOTA PLANTS 
O. A. Stevens 
The fact that North Dakota is only partially included within the limits 
used by eastern and western manuals, and that its northern boundary is 
also that of the United States, makes the composition and distribution of 
its flora a question of considerable interest. The present paper is offered as 
a preliminary analysis of our knowledge of the subject. It is based upon 
the records published by Bergman (3)^ and upon the writer's observations 
made during occasional visits to nearly all parts of the state in the years 
1910 to 1919. The number of vascular plants found within the state as 
listed by Bergman is 966. This is by a conservative limitation of species. 
Lunell (8), using narrow specific limits, lists about 1,300. It is thus seen 
that the number is small as compared with that of other states. This is 
probably due to a comparative lack of diversity of conditions, as there is 
no unexplored area which might add materially to the list. 
To a botanist unfamiliar with the plants west of the range of the eastern 
manuals, the first feature of interest is the western plants. To the writer 
it has always seemed that the most natural limit of the western forms is the 
Missouri River in the southern part of the state and a line continued across 
the state in the direction of its course there, which would be about longitude 
100° 30' to 101° 30'. A few of the western forms extend eastward as far as 
the Sheyenne River. A preliminary division into general groups according 
to the distribution of the plants in the state gave the following results : 
I. Eastern; not west of Red River, Devil's Lake, or Turtle Mountains 25% 
n. Eastern; reaching the Missouri River 10% 
III. Western; west of the Missouri River 11 % 
IV. Western ; extending east to the Sheyenne River 8 % 
V. CosmopoHtan 30% 
VI. Introduced 16% 
These figures are somewhat unsatisfactory, especially as to the second 
group, this being not well separated from the first. There is an apparent 
lack of records from the southern two thirds of the state from Jamestown 
west to the Missouri River. It is evident, however, that the western ele- 
ment is comparatively small. A more critical study of some of the principal 
families and orders with regard to their North American distribution shows 
the following results when grouped as in the preceding list. The number 
of species included in eastern (10) and Rocky Mountain (4) manuals is 
^ The nomenclature and arrangement of his work is followed in this paper. 
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