50 THE AMERICAN BOTANIST 



has almost entirely replaced the native hunch grasses. Ex- 

 tensive patches of Salsola pcstifcr in late September give a 

 characteristic ruddy glow that alternates with the blaze of 

 rabbit-brush {Chrysothniniis) up and down the slopes of the 

 entire valley. It is: remarkable how many weeds from the 

 Old World are spreading here and how few of the native 

 plants resist intrusion and become weeds. Among the most 

 striking examples of the former are Lcpidhini pcrfoliatimi, 

 Cheirinia repanda and Atriple.v laciniata, tliis last not re- 

 corded from any other place in the United States. The plant- 

 ing of European sugar beet and grain seed in many places west 

 of the mountains easily accounts for the presence of the first 

 two while the last seems to be closely connected with the large 

 European population of Pocatello. 



The seasonal aspects may be divided into pre-vernal ver- 

 nal early aestival, late aestival and autumnal. 



The pre-vernal aspect covers the time from the beginning 

 of plant growth to about the end of April. During this period 

 the grass becomes green, the buds of the trees swell and burst, 

 and pussy-willows, and such other tree blossoms as appear 

 before the leaves, expand. Buds and young shoots of Arte- 

 misia and Chrysothamus soften and afford good browsing for 

 hungry herds. The bristly points of Phlox and other pun- 

 gent -leaved perennials become tender. Basal rosettes of such 

 plants as Arahis, Senecio, and Cheirinia are conspicuous and 

 succulent tufts of larkspur as well as the tender green shoots 

 of poison sego offer dangerous temptations to hungry animals. 

 A very few herbs flower at this season. (Frittilaria ptidica, 

 Phellopterus Utahensis, Cogszvellia Jonesii and Microsteris 

 micrntha). The last mentioned is the earliest. I have found 

 it in bloom March seventeenth on the grassy slopes below the 

 cedars when scarcely an inch high. 



