284 NEBRASKA STATE HORTICULTURAL SOCIETY. 



and other holes in the more tenacious soil. This results in the develop- 

 ment of a soggy soil where one finds such moisture-loving plants as 

 marsh mint (Stachys palustris), Solomon's seal (Vagnera stellata), heal 

 all (Prunella vulgaris), long-bracted orchid (Coeloglossum bracteatum), 

 rush (Juncus balticus), liverwort (Marchantia polymorpha), mosses 

 (Bryum sp.), etc. The cow tracks are frequently filled with filamentous 

 algae and free-swimming animals such as Euglena. 



The willow thickets, althcugh quite striking structures on the lower 

 slopes, are still well within the bunch-grass association. But as one gets 

 down into the valleys proper the bunch-grasses, and also many of their 

 associates, are left behind. There are two quite distinct types of valleys 

 in the Sand Hills. The diy valleys are relatively short and narrow and 

 with a good covering of grasses which often form a close sod, but with no 

 standing water. The well-developed sod is a condition that causes the 

 vegetation of the valleys to be distinct in appearance from that of the 

 uplands, with the tufted appearance of the bunch-gi'ass association. 

 Such dry valleys are very common in many portions of the Sand Hills. 

 They yield an abundant crop of fine hay during moist seasons and often 

 afford very fine forage because of the presence of buffalo grass (Bulbilis 

 dactyloides), and grama grass (Bouteloua oligostachya) in considerable 

 quantity. The soil of these valleys is not so sandy as the uplands. This 

 with the water table nearer the surface makes possible the culture of 

 certain agricultural crops, if the proper care is taken to prevent the soil 

 from blowing. When the sod is broken in a dry valley where a consid- 

 erable area of nearly flat soil is exposed to the wind, the blowing soil 

 frequently prevents the growth of field crops or any other plants. 



The fiora of the dry valleys is very similar to that of the prairie 

 regions of the state, being especially rich in grasses. The principal 

 widely distributed plants of the dry valley are: switch grass (Panicum 

 virgatum), wheat grass (Agropyrum pseudo-repens), blue joint grass 

 (Calamagrostis canadensis), wild rye grass (Elymus canadensis), red 

 top (Agrostis alba), tickle grass (Agrostis hiemalis), rattlesnake grass 

 (Panicularia americana), and a number of sedges. All of these species 

 are valuable forage plants and they are all included in most of the hay 

 that is put up from the valleys. Besides these economic plants there are 

 many other herbaceous members of the prairie flora that have wandered 

 into the Sand Hills and have found congenial homes in these dry valleys. 



The river flats properly belong to the dry valley type, since here we 

 find a soil free from surface water and with all of the above species of 

 plants often growing in profusion. These low flat areas extend from 

 the banks of the river back sometimes several hundred yards to the 

 bases of the hills. These flats or "benches" are well developed along 

 the Middle Loup River. The river winds across the flats in a very irregu- 

 lar course, sometimes cutting close to the hills on one side and then 

 shooting across to the hills on the opposite side of the flat. On these 

 flats and along the bank close to the stream occur the most of the trees 

 of the region. Thickets of plum (Prunus americana), and cherry (Prunus 



