so BULLETIN 791, U. S, DEPAETMENT OF AGRICULTURE. 



prominent aAvn, which, when the plant approaches maturity, becomes 

 rather stiff and is objectionable to stock. This lack of palatability 

 of the seed heads, however, in no way impairs the value of the herb- 

 age. The fact, however, that the seeds after they become well formed 

 are consumed to only a very limited extent by stock, accounts in part 

 for the unusual aggressiveness ^ of porcupine grass. 



The palatability andi forage value of the yellow brush dominant is 

 comparatively low, so that where this species occurs in such abund- 

 ance as appreciably to decrease the stand of other palatable plants 

 the carrying capacity of the lands is considerably lower. While 

 sheep and cattle browse the leafage and flower clusters to some ex- 

 tent, yellow brush can not be classed as a plant of sufficient forage 

 value to be seriously considered in the management of the range 

 with a view of increasing its abundance and luxuriance of growth.- 



A large proportion of the secondary perennial species character- 

 istic of the poreupine-gra^-yellow -brush consociation, particularly 

 the grasses, are probably first in importance among our valuable 

 forage species. Practically all of the blue grasses, the fescues, the 

 bromes, spiked trisetum, and mountain June grass, which occur in 

 varying abundance throughout this consociation, are inferior to none 

 as forage, cattle, sheep, and horses grazing them with relish at all 

 times in the season. Likewise^ some of the more conspicuous non- 

 grasslike perennials, like yarrow, are good forage plants, though as 

 a rule the nongrasslike species are grazed much more closely and 

 with greater relish by sheep than by cattle and horses.^ It is quite 

 evident, therefore, that the porcupine-grass-yellow-brush lands gen- 

 erally are w^ell suited to the common use of stock, that is, the joint 

 grazing of cattle, horses, and sheep. In this respect, then, the porcu- 

 pine-grass-yellow-brush consociation diifers from that of the wheat- 

 grass type, which in its highest development is best suited for the 

 grazing of cattle and horses. 



^The seeds of porcupine grass are usually high in viability and reproduction is greatly 

 fostered by the self-burial device of the seed, the alternate twisting and untwisting of the 

 awn coupled with the sharp-pointed appendage at the base of the seed. For a discussion 

 on this point see Journal Agri. Research, vol. 3, No. 2 : 118-119, 1913, and U. S. Depart- 

 ment of Agriculture Bulletin No. 545 : 9-10, 1914. 



2 Sheep browse yellow brush with more relish than cattle. Because the foliage remains 

 green lat« in the autumn after the herbage of most plants has dried up, sheep browse 

 yellow brush more closely in the autumn than at any other time in the season. Even so, 

 however, this plant furnishes only a small amount of rather inferior feed. 



^ Cattle and hoi'ses prefer grass to nongrasslike plants, such as weeds and browse. 

 Sheep, on the other hand, pi-efcr the weed and browse type, and consume a relatively 

 email proportion of grass. Exception to this statement has been recorded when the grass 

 is unusually palatable and the nongrasslike species are of an inferior kind. Therefore, 

 where the vegetation consists of about the same amount of palatable weeds as of grass, 

 the proportion of four sheep to one cow unit usually results in the most economic utiliza- 

 tion of the forage crop. On a pure or practically pure grass range, on the other hand, 

 cattle alone, or cattle and horses, usually afford the most economical utilization of the 

 forage. On a strictly weed range the best utilization may be expected from the grazing 

 of sheep only. 



