WEEDS. 17 



ing, only a moderate growth of the perennials, but at least tenfold as 

 much as there was last year, and a very heavy growth of the annuals. 

 Judging from what has taken place upon the first large inclosure, the 

 annuals will gradually give way to the perennials during the next 

 four or five years and at the same time withstand a considerable 

 amount of grazing. 



Below an altitude of about 3,500 feet we come to the desert proper, 

 where the summer grasses are mainly of the annual type, always have 

 been, and probably always will be. Below this altitude the only 

 perennial grasses are those which are favored by occasional irrigation, 

 in long arroyos and swales, where the drainage from higher levels 

 spreads out over them. There is no hope of establishing perennials 

 upon the lower, unirrigated mesa lands. When rains are favorable 

 the low-lying regions will produce some indifferent feed in the shape 

 of annuals, and that is all that can be hoped for them. 



PECULIARITIES OF THE FEED. 



The appearance of the feed upon the ground is deceptive in any 

 desert country, but more especially in the area described in this bul- 

 letin. The growth is invariably thin, but it may be quite tall, espe- 

 cially in favorable years, making difficult an estimate of the quantity 

 of feed produced. This is true of the growth in general upon a desert 

 region. The most deceptive grass of all is the one locally known as 

 black gama ( Mulilenbergia porteri) . (See PI. TV, fig. 1 . ) In early days 

 this grass was exceedingly conspicuous, growing in tangled masses 2 

 to 3 feet high, both in clumps of shrubbery and in the open. The 

 pioneer stockman calculated the productivity upon what he saw of 

 this species, supposing that he was dealing with a grass of ordinary 

 character. But the pioneer saw three or four years' growth, for the 

 culms of this grass are perennial, only the terminal joints dying back 

 each season. When, therefore, an area is unpastured for a time there 

 is actually an accumulation of feed from year to year of this grass 

 and some others, while the ordinary grasses die and grow up again 

 from the roots each year. The deception is really serious, as is readily 

 seen if one mistakes three or four years' growth for one and stocks 

 the land accordingly. This is precisely what has happened in many 

 cases. It is no wonder that some managers of stock companies 

 insisted that the country could not be overstocked, nor, indeed, would 

 it probably be if the production which the pioneer saw could be 

 repeated with certainty each year. 



WEEDS. 



There are really but two weeds in the inclosure, but they are both 

 somewhat serious. One is one of the rayless golden-rods (Isocoma 

 coroTWpifolia) (PI. IV, fig. 1), not distantly related to the sheep weeds 



177 



