TRUE PRAIRIE 273 



speciosa, rigida and nemoralis, Helianthus rigidus, occidentalis , grosse- 

 serratus, maximiliani and orgyalis, Artemisia vulgaris and dracuncu- 

 lus, Liatris scariosa and punctata, Vernonia jasciculata, and Salvia 

 pitcheri (cf. Sampson, 1921). 



Proclimaxes. The most interesting and important of these is the 

 tall-grass community, which occurs regularly as a postclimax in val- 

 ley and lowland, as w^ell as in many areas of sandhills or dunes. This 

 has often been termed low prairie, in allusion to its habitat but not 

 its stature. Under the impact of settlement, the tall species of Andro- 

 pogon in particular have moved up the slopes in the wake of the dis- 

 appearing mid grasses, giving rise to the adage of pioneer days that 

 bluestems followed the settler. This consequence has been so general, 

 especially in the east and south, that most of the true prairie relicts 

 today are modified and many of them dominated by tall grasses. On 

 the surface they give the appearance of being climax dominants, but 

 in reality they constitute a disclimax caused by the varied and often 

 obscure disturbance incident to settlement. In the western portion of 

 the association another disclimax is to be found in pastures, where con- 

 fined grazing has led to the production of a short-grass sod similar 

 in most respects except extent to that of the mixed prairie. 



Valley woodland constitutes a postclimax to the true as well as to 

 the mixed prairie, though the higher precipitation renders it much 

 richer in tree dominants. Relicts of similar composition also occur in 

 extensive tracts that simulate climax forest, owing to the local com- 

 pensation afforded by sandy soil or mountain outliers, as in central 

 Oklahoma and along the western edge of the Ozarks. 



Influents. The bison was originally plentiful (estimated at 12 

 million or a bison to 20 acres) throughout the true prairies. Its wal- 

 lows and paths through the river-skirting woods may still be seen in 

 Illinois. In 1679, at the beginning of winter, LaSalle saw bison stuck 

 in a marsh near South Bend, Indiana; in 1680 he found the prairie 

 near Morris, Illinois, "alive with buffalo." It disappeared east of the 

 Mississippi River about 1800; according to an Indian tradition, most 

 of the herd in Illinois was killed by a blizzard about 1775 (M. B. 

 Shelford, 1913). There was some competition with elk near wooded 

 areas, especially in summer. This was particularly the case in the 

 true prairie areas, where valley forest afforded shelter and winter 

 browse for the elk. 



The gray or buffalo wolf {Canis nubilus Say) was originally de- 

 scribed from the true prairie country of Iowa. The coyote {Canis 

 latrans Say) is confined to the true and subclimax areas and is fond 

 of the forest margins of the region; it still occurs in Illinois and In- 



