56 BULLETIN 545, U. S, DEPARTMENT OF AGRICULTURE. 
confined to any one soil type. Such plants, however, do not afford 
nearly the amount of forage those do which are found generally in 
the more open habitat (usually referred to as drought-resistant 
plants), where the soil is not finely disintegrated, is less well supplied 
with organic material, and has a wilting coefficient notably lower. 
A relatively small proportion of the range lands are wet throughout 
the growing season; while bogs, marshes, and the like almost invari- 
ably support a more luxuriant stand of vegetation than any other, 
the herbage usually lacks in two essentials — palatability and nutri- 
tiousness. Those who have observed stock as to their choice of forage 
have noticed that sheep avoid marshes and wet habitats to a marked 
degree ; that cattle drift to the better drained lands for most of their 
feed; and horses, if unaccustomed to marsh vegetation, such, for 
example, as sedges and rushes, graze it eagerly for a couple of days, 
after which they will not remain on the succulent feed if any other 
is available. Campers and mountain workers have found that their 
pack and saddle animals can not do the work when feeding on marsh 
and bog vegetation that they can on drier feed. Also, stockmen 
have found that fat made on succulent feeds is not of a solid char- 
acter and in the case of long drives to market or of shipment shrinkage 
is abnormally heavy. 
LIFE HISTORY. 
To aid the reader in comparing the different phases of growth, the 
time of seed maturity, and the viability of the seed crop produced by 
the various forage species discussed, the results are summarized in 
Table 3. 
It will be seen that the time of the flowering period varies more 
widely than that of seed maturity. This is due primarily to the 
greater contrast between the moisture and temperature of the 
soil during spring than in late summer and autumn seasons. 
Growth, of course, starts more promptly and vigorously in the 
better drained and consequently warmer soils than in the moister 
and cooler situations. Owing to the more uniform physical condi- 
tions in a given life zone as the season advances, the seed maturing 
period is much more uniform and is completed in less time than that 
of flower-stalk production. All species and situations considered, 
the flower stalks are mainly produced between July 5 and August 10, 
and the seed matured between August 1 5 and September 1 . While 
the time of flower-stalk production and period of seed maturity are 
influenced by the physical factors, even greater contrast is brought 
about by weakening of the vegetation due to overgrazing. Plants 
seriously weakened through abusive grazing are late in producing 
flower stalks and in maturing the seed. In extreme cases no flower 
stalks are produced, and, in general, such seed as is produced has 
little or no germinative power. Plants less seriously weakened pro- 
