20 



MINNESOTA BOTANICAL STUDIES. 



The prominent-flowered blazing stars and prairie clovers make 

 a much greater impression on the eye than species which are far 

 more abundant, and the same thing is true to a less degree of 

 many other species. To insure accurate or even approximately 

 accurate results, it is necessary to resort to some method of actual 

 count. 



Actual count is usually practicable only when copious, gre- 

 gario-copious or sparse plants are in question. But it is only 

 with respect to such species, which are as a rule secondary in 

 formations, that it is important to determine minutely the grade 

 of abundance manifested. 



During the past season, in order to determine the actual quan- 

 titative relations of the copious and gregario-copious species, 

 we have made a large number of enumerations of the individual 

 plants of each secondary species present in plots five meters 

 square in characteristic formations of each of the four phytogeo- 

 graphical regions represented in Nebraska. The plot used, five 

 meters square, is as large as can be used to insure accuracy in 

 counting. The deficiences resulting from the small size of the 

 plots are corrected by taking a large number of plots at each 

 station and averaging the results. There is a surprisingly close 

 agreement in figures obtained from plots in widely separated 

 stations in the same district, provided reasonable care is taken 

 to locate them in typical situations. 



By way of illustration, a number of observations are given in 

 full. These are not averages, but are the actual counts as taken 

 in the field. The two immediately following were taken on the 

 prairie 14 miles northeast of Lincoln in the prairie grass forma- 

 tion ( Sporobohcs-Koeleria-Pamctim ). The second was made 

 about 400 yards distant from the first. 



