44 BIG SPRING PRAIRIE. 



promises to hold out for some years to come. It is also 

 holding its own in a few other well drained areas. 



In the depressions of area Fof Map II, Typha lat- 

 ifolia (Cattail) was very abundant before the last deep- 

 ening of ditch, after which a gradual decrease in abund- 

 ance occurred. Yet it was fairly common even in 1900, 

 the year before the greater portion of this area was 

 ^Drought under cultivation. 



Isnardia palustris (Mud Purslane) and Proserpinaca 

 palustris (Mermaid Weed) are other striking examples 

 of plants yielding slowly to the changed condition. A 

 specimen of Proserpinaca was found late in the Autumn 

 on a piece of ground which had been planted to pota- 

 toes. It survived in spite of cultivation, but it had 

 changed its general habit. Instead of growing long 

 and slender, it formed a dense mat about eight inches 

 in diameter, which closely hugged the ground. 



Salix myrtilloides and Betula pumila are frequent- 

 ly found growing along the well drained banks of 

 ditches three to five feet deep, although they are char- 

 acteristic swamp plants. The evident explanation of 

 this lagging of eflfects is found in the facts of well devel- 

 oped root system of most of the plants cited in connec- 

 tion with the great water content of the muck of this 

 prairie. 



5. Plant Societies of the Prairie. 



Although there is only a moderate difference in the 

 surface level of the prairie, yet there are quite distinct 

 plant societies flourishing in close proximity to each 

 other. Some times the difference in surface level is 

 not more than one or two feet yet on the slightly higher 

 portion, a mesophytic forest formation may have been 

 developed, while a hydro-mesophytic prairie society 

 may be firmly established on the slightly lower level. 

 Again on another part of prairie considerably higher 

 than the wooded portion, a prairie society may behold- 

 ing sway. Mere elevation can not reconcile these 



