RANGE FEKI>. 58 



tiltliou^ih liiuilcd ill qiiantilv, uiakes denst' mats over small areas. It 

 is to two small annual species, Trifolhun gracilentum and T. tri<len- 

 tatiim^ that the greatest interest attaches, for there are indications that 

 these an» i?itroduced species which are just heg-inniug to assert them- 

 selves in the southern part of Arizona. In March, 1903, there was 

 good feed produced by th(vsc species in several localities in the AVillow 

 Spring ^Mountains. Heing associated here with aiiilerilla and in the 

 direct path of the early sheep migrations from California, it is quite 

 probable that these have been introduced in wool from California and 

 western Great Basin points, where they occur in considerable profusion. 

 It is interesting to note that the maturity of these two species occurs 

 about two months earlier in these mountains than in the Sierra Nevada 

 Mountains east of Fresno. Cal. There is a bare possibility that a 

 sj'stematic effort to distril)ute these to other mountain ranges, either 

 by securing the seed from the situations where it is produced most 

 abundantly or by systematic herding in the season when the clovers 

 are ripening, may result in (>stal)lishing them, thereby increasing the 

 feed in the foothills and lower mountains. It is (piite certain that 

 they will be of value only in the foothills, below the limit of winter 

 annuals. 



ALFILERILLA." 



Upon the areas where the aiiilerilla is thoroughly established there 

 is no other plant, unless it be Indian wheat, which can compare with 

 it in the quantity of feed which it produces upon the desert mesas for 

 winter and spring grazing. There appears to be no doubt that it was 

 introduced into Arizona by sheep from California points. It is now 

 well distributed as far south as the northern slope of the Santa Cata- 

 lina Mountains and up the San Pedro Valle}' as far as Benson. It has 

 not spread very much east of the San Pedro Kiver. From here it 

 extends northward and westward through the desert areas and high 

 into the plateau regions on the north and west sides of the Prescott 

 liighlands; thence westward into California. There are scattering 

 plants of it all over the Territory, but it is in the region indicated that 

 it is of importance. It even occurs commonl}^ upon the San Francisco 

 Mountains at an altitude of 7,000 feet, but it is never abundant enough 

 to be of any importance. It is much more abundant in the vicinity of 

 Prescott (5,320 feet), but does not produce as much feed as upon the 

 west side of the Prescott highlands, where it extends up to Iron 

 Springs (6,032 feet). In this region it is well established all the way 

 from Wickenl)urg (2,06T feet) to Iron Springs, in the edge of the pines. 

 It appears to be psrfectly at home in the scrub-oak area below the 

 pines, where it remained green during the season of 1903 as late as 

 the last of M^y. 



«See Plate VI. 



