Apr. IS, igao Nolvve Vegetotiofi of Northern Great Plains 



65 



The dominating species are Bouteloua gracilis {B. oligostachya) and 

 Stipa comata, which form a distinct association. This is an association 

 composed of Bouteloua gracilis, which is typical of the short-grass forma- 

 tion, and Stipa comata, which is a typical long-grass species. This asso- 

 ciation is dominated by the Bouteloua. Sarvis ^ has described in a paper 

 other sections of western North Dakota which show the same dominating 



species. 



COMPOSITION OF THE VEGETATION 



In Plate 1 2 is illustrated the general character of the vegetation on the 

 prairie in the Mandan region. In 191 5, when this photograph was taken, 

 the season was very favorable, and all plants reached a maximum devel- 

 opment. The composition of the vegetation is thus very clearly illus- 

 trated. 



In the following list of plants the arrangement of species is in the 

 order of abundance. The order of the primary and secondary species 

 is subject to slight modifications as the studies are extended. The order 

 of the dominant species was determined by measurements from quadrat 

 maps and in the field. The order of the primary species, other than 

 grasses, was determined by count. The secondary species are listed in 

 the estimated order of their abundance. 



DOMINANT SPECIES 



Bouteloua gracilis 

 Stipa comata 



Artemisia gnaphalodes 

 Koeleria cristata 

 Solidago pulcherrima 

 Agropyron smithii 

 Artemisia dracunculoides 

 Psoralea argophylla 

 Andropogon scoparius 



Muhlenbergia cuspidata 

 Lacinaria punctata 

 Calamovilfa longifolia 

 Agropyron caninum 

 Bouteloua curtipendula 

 Comandra pallida 



Carex filifolia 

 Carex heliophila 



PRIMARy SPEaES 



A rtemisia frigida 

 Stipa viridula 

 Eschinacea angustifolia 

 Aristida longiseta 

 Polygala alba 

 Stipa spartea 

 Ratibida columnaris 



6BCONDAKY SPEQES 



Aster multiflorus 

 Petalostemon purpureum 

 Petalostemon candidum 

 Lactuca pulchella 

 Vicia sparsifolia 

 Agropyron tenerum. 



The grasses, other than the dominant species, are in the estimated order 

 of abundance. It is difficult to make individual counts of them, since 

 they usually occur in bunches. If bunches or mats were considered as 

 single plants and enumerated as such the number would have no signifi- 

 cance when compared with that of other plants which usually occur 

 as individuals. 



'Sarvis, J. T. native grasses of western north Dakota. Paper presented before the Ecological 

 Society of America at its annual meeting in New York in 1916. 



