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 15' 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- 



