22 THE BIOLOGY OF HARDING COUNTY 



2. GRASSY FLATS OR TERRACES ALONG THE 

 VALLEYS. 



1 i ) This biologic association is related to the steppe ; it also 

 sometimes adjoins the wooded bottoms. Its conditions are similar 

 to those of the steppe, but not so severe. There is no more, and 

 perhaps there is less rainfall, but there is more ground water be- 

 cause of two reasons: (a) The run off from the adjacent eleva- 

 tions, (b) The terraces are lower and consequently nearer the 

 water table of the district. 



(2) Some of the conspicuous plants and animals of the grassy 

 Hats. Almost all of the plants of the steppe occasionally grow 

 here. Since the wash of the rain brings down the seeds of al- 

 most all the steppe plants it is very reasonable that sporadic repre- 

 sentatives should occur. The predominant vegetation, however, 

 is somewhat different. There is a much larger percentage of the 

 wheat grass (Agropyron*) and decidedly more prickly pears. 

 There are many .large patches of the buckbush (Symphoricarpos). 

 The wild rose (Rosa arkansana) is often associated with these 

 patches. Brome grass (Bromus) is frequently prominent and 

 with it the grass-like Collomia. Other plants which are usually 

 in evidence are burr tomato (Solatium), blue-joint (Calamagrostis) 

 wild-rye (Elymus), red-top (Agrostis). In addition there are 

 several species each of Atriplex, Chenopodium, Erigeron, Solidago, 

 Helianthus and Artemisia most notable of which is the true sage 

 brush and the lancelate sage. As far as my observation goes 

 there are decidedly fewer flowers than on the steppe. 

 Locally on the the plains and rarely on the steppe are 

 blowouts or "hardpan" spots which have a peculiar flora. The 

 small or fragile prickly pear (Opnntia fragilis) here replaces the 

 larger Opnntia polycantha of the loam and is sometimes exceed- 

 ingly plentiful The grass is chiefly the alkali grass (Distichlis). 

 Three flowers which we found only on such spots are Talinum, 

 Suaeda, Monolipis. 



The conspicuous mammals making these flats their breeding 

 places are the prairie dog (Cynpmys*) and in these colonies 

 animals that prey on them, especially the weasel (Putorius) and 

 rattlesnakes. The western cotton-tail rabit (Lepus) is often found 



*For specific names see the technical lists of species which follow 

 this section of "the biology." 



