30 BULLETIN 791, V. S. DEPAETMEXT OF AGRICULTURE. 
prominent awn, 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 x of porcupine grass. 
The palatability and 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. 2 
A large proportion of the secondary perennial species character- 
istic of the porcupine-grass-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. 3 It is quite 
evident, therefore, that the porcupine-grass-} T ellow-brush lands gen- 
erally are well 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 differs from that of the wheat- 
grass type, which in its highest development is best suited for the 
grazing of cattle and horses. 
1 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 late 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. 
s Cattle and horses prefer grass to nongrasslike plants, such as weeds and browse. 
Sheep, on the other hand, prefer the weed and browse type, and consume a relatively 
small 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 band, 
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. 
