Pool : THE VEGETATION OF THE SANDHILLS OF NEBRASKA 297 



times reach to the water table. An average diameter of these more 

 or less cylindrical holes is about twenty inches and that of the soil 

 columns topped with plants is about the same. This condition may 

 result in almost any part of the wet meadow with firm soil and, as 

 might be imagined, introduces a surface character often hidden by 

 the vegetation, that becomes dangerous to animals that are pastured 

 in such places. 



The relation of the two ferns to light is quite different. Dryop- 

 teris is rarely seen within the shadier portions of the wet meadows 

 or in the shade of taller associations, but Oivoclea is a frequent mem- 

 ber not only of the more shaded portions of this association, but is 

 also seen in the more open woodlands near the streams of the region. 

 The association becomes somewhat mottled when the two dominant 

 species control alternating areas. 



THE HAY MEADOW ASSOCIATION 



The many broad valleys of the northern half of the sandhill 

 region, and less so also the valleys of the southern portion, reveal 

 the presence of wide expanses of flat, but relatively dry soil above 

 that of all of the lowland associations thus far considered. The 

 area of such land varies naturally with every valley. Some narrow 

 valleys with finger lakes show practically no flat land between the 

 marsh or wet meadows and the bunch-grass upland. In many 

 cases, however, much of the valley floor lies between the wet 

 meadows and the first hills. This type of land is covered in the main 

 by grasses and other plants which are annually mowed by ranch- 

 men along with parts of the wetter meadow for hay. Thousands of 

 tons of valuable product are thus derived from the lowlands to 

 supplement the upland forage crop which is very seldom cut for hay. 



The soil of the association is usually a fine sandy loam with con- 

 siderable humus and very excellent water-content relations as is 

 shown by the fact that this sort of land, when broken up and put to 

 agricultural uses, produces goodly yields of various field and garden 

 crops. The water-table lies but a short distance beneath the sur- 

 face. This fact has not been properly appreciated by homesteaders 

 and ranchmen who have attempted to grow deep-rooted crops such 

 as alfalfa upon this land. Commonly these persons have witnessed 

 the "drowning-out" of a crop that might be grown on higher situa- 

 tions even in the "arid sandhills." Surface water is usually present 

 over the lower portions of this association where it joins with the 



