GEAZING EANGES IN SOUTHERN AEIZONA. 11 



Griffiths ^ and Thornber -. Certain characteristics of this grass need 

 further emphasis, however, since by virtue of them it offers possi- 

 bilities not shown by many other grasses of the region. It endures 

 great extremes of temperature and dryness; it grows upon some of 

 the poorest and driest of the gravelly mesa soils; it occurs at alti- 

 tudes ranging from about 2,000 to over 4,000 feet ; it is excellent feed ; 

 its stems are perennial and die back but a short way at the tip each 

 winter, thus furnishing feed at any time in the year. These are its 

 good points. It must be remembered that its growth is very slow, 

 dependent entirely vipon the water supply of a very dry region; 

 that its seeding habits are poor, and that conditions for germination 

 are poor even when viable seeds are produced ; that it is easy to over- 

 estimate the carrying capacity of a previously unstocked range of this 

 kind of grass, because the growth present is that of several seasons. 

 These are the bad points. This grass usually occurs under the 

 bushes and may be found sparsely scattered over all the mesa country 

 in such protection. It certainly will not bear any degree of over- 

 stocking, but it is at least doubtful if students of grazing conditions 

 (the writer included) are warranted in treating this grass as not 

 worthy of much consideration, as has been very largely their habit 

 hitherto. 



The way that this grass (probably the best feed of its distribution 

 area) has managed to persist in a region which has been thoroughly 

 denuded of everything in the way of stock feed is of itself noteworthy. 

 And observations in the reserve have demonstrated clearly that under 

 protection from animals it is capable of dominating areas where it 

 was thought to be almost a negligible factor. When the fence was 

 first built it was hard to find any large plants of this species,^ and 

 they w^ere always under bushes. After 11 years of protection it is 

 fairly common all over the reserve below the 3,800-foot contour, 

 and, while the old plants are more apt to occur in the bushes, their 

 presence there is not universal nor due to the necessity of shade or 

 protection, but probably because such situations are more favorable 

 for the germination of the seeds. Within the past four years, since 

 seed plants have become tolerably numerous, the species has spread 

 quite rapidly in the northwestern quarter of the reserve and has put 

 a considerable crop of good feed on an area that previously pro- 

 duced a very small crop of poor feed. And there is little doubt that 

 under protection this plant will come to jjominate much of the re- 

 serve, especially that part of it where the other perennial grasses 

 grow but poorly. The spread and development of this plant under 

 protection is strongly corroborative of the claims made for it by the 



1 See Bureau of Plant Industrj' Bulletin 177, p. 17. 

 ' - See Arizona Experiment Station Bulletin 65, p. 279. 



3 See Bureau of Plant Industry Bulletin 177, PI. IV, flg. 1. 



