58 IVyoining- Experiment Station. 



City, from which point the surrounding mountains and 

 valleys were scoured and resulted in 123 numbers. The 

 third expedition left for Laramie Peak, seventy-five miles 

 distant, on August 3 and returned with 117 numbers. 

 The fourth made two camps, one in the Centennial Valley 

 and one at the La Plata Mines near the summit of the 

 Medicine Bow (Snowy) range. From these two points 

 adjacent territory was worked and yielded 192 species, 

 many of them quite rare. 



Besides the above species, there were collected at 

 various times during the season 135 numbers, making a 

 total for 1895 of 670 numbers. As these were all in du- 

 plicate, approximately in tens, the total number was 

 near 6,700. 



Of the 670 species about one-half are new as com- 

 pared with the collections of 1894. 



PLANT ZONES. 



Recent writers have made much of plant zones as 

 limited by given lines of elevation. There is, no doubt, 

 considerable truth in the theory that fairly well marked 

 belts are found, but I think it is possible to overestimate 

 the importance as well as the distinctiveness of such 

 zones. There are so many other factors that enter into 

 the problem, such as moisture, soil and exposure that its 

 solution becomes peculiarly difficult. The zones sink and 

 rise in conformity as much with the configuration of the 

 land, the absence or presence of arboreal vegetation, the 

 character of the soil and the amount of moisture as in 

 respect to the altitude. The monotony of the grassy 

 plain gives place to a veritable garden if but a few clay 

 hummocks or stony points and ravines interrupt its 

 interminable length. Seven thousand feet with one ex- 



