748 Journal of Agricultural Research voi.vi.No. 19 



uals, again completely appropriating areas left barren because of the 

 death of upland plants that were unable to grow in the new environment. 

 These two elements furnish the foundation for two distinct lines of 

 development which the upland may undergo in its transformation. The 

 value of the respective components may be noted profitably now. 



Agropyron Smithii, strangely enough, seems to be the only species that 

 develops either vigorously or abundantly. There are at least two pos- 

 sible reasons for this. Attention has already been called to the fact that 

 it prefers the slopes where the moisture content is greater and more uni- 

 form, so it may be the only species that is capable of using to advantage 

 the increase in available moisture. Or it is not impossible that some of 

 the other kinds, under the new conditions, become indistinguishable from 

 the true A. Smithii, with which they not infrequently grow and from 

 which they are separated by such characters as pubescent glumes and 

 comparative awn development, characters which there is good reason to 

 believe are easily modified by environmental factors. 



Koeleria cristata and Bouteloua oligostachya and the two sedges noted 

 are valuable, but the controlled-flooding method of irrigation caused their 

 almost total disappearance by the second season. 



Arabis hirsuta develops best,, as will be evident when controlled irriga- 

 tion is used, becoming one of the few native weeds. 



Antennaria parvifolia is an everlasting nuisance on comparatively dry 

 places. Plate CII, figure 1, shows its excessive development along a 

 meadow edge. It readily succumbs to too much water, but unhappily 

 the regular order of succession seems to mean that it will usually be 

 replaced by Pedicularis crenulata, the weed that so frequently ruins 

 meadows. 



Grindelia subalpina reaches its greatest development the second season, 

 as a weed. 



Hordeum jubatum is not necessarily a meadow weed by any means, but 

 since it occurs as such in this region it is included in this list of meadow 

 plants. It is sometimes fed, but is dangerous because of the barbed awns. 

 Like wheat-grass, interest in it has just begun. 



Sporobolus brevifolius and Plantago eriopoda are of saline or subsaline 

 habitat, and therefore their presence is significant. When an alkaline 

 place appears, the invasion of this valuable x grass is the best thing that 

 can happen ; if it succeeds in establishing itself, it uses a spot that would 

 be occupied by the plantain or later by one or both species of Sagittaria. 

 (See "Minor plants," pp. 757-758.) 



Juncus longistylis is destined to play an important part in the meadow 

 development. Its nutritive value is rightly regarded as good, but it 

 suffers by comparison of its analysis with that of wheat-grass. 



1 Knight, H. G., Hepner, F. E., and Nelson, Aven. Op. cit. 



