THE ALPINE FLORA OF MT. SHASTA. 137 



•meadows above the limit of trees, and the vast treeless deserts 

 towards the south. Dr. C. Hart Merriam in the Proceedings 

 of the Biological Society of Washington (Vol. VII., p. 24) 

 has discussed these two distinct regions under the names 

 Boreal and Sonoran, the Arctic division of the Boreal region 

 being above the limit of trees. This Arctic division and the 

 Sonoran region, alike in the almost total absence of trees, are 

 quite dissimilar in all other respects. The same genus is not 

 often represented in both, and identical species have not yet 

 been reported. 



The Sonoran vegetation consists chiefly of low spiny 

 shrubs and annual herbs. The shrubs are distributed, with 

 very little variation, over an immense area of country embrac- 

 ing parts of Colorado, Utah, Nevada, New Mexico, Arizona, 

 Texas and California. The comparatively few species of 

 perennial herbs have a distribution almost as wide; the 

 annuals, with species numerous and frequently localized, 

 show a stroug tendency to variation. 



The flora of the lofty mountain peaks belongs seemingly 

 to another world. Here, tall shrubs and annuals are scarce, 

 giving place to perennial herbs and low prostrate shrubs, re- 

 sembling herbs, that hold possession of the soil with a root 

 surface that is remarkably large and out of all proportion 

 to the part above ground. The plants have familiar 

 names; every one knows what is meant when we speak of 

 gentians, primroses, potentillas, saxifrages, anemones, butter- 

 cups, clovers, stone- crops, asters, erigerons, valerians, drabas, 

 chickweeds, willows, sedges, rushes and grasses. In fact, 

 the genera are widely spread throughout the Arctic zone in 

 both hemispheres, and on all the lofty peaks of the northern 

 hemisphere. In a list of eighty-five genera of the alpine 

 zone in the Rocky Mountains only six are not generally 

 represented throughout arctic-alpine regions, while in a list 

 of one hundred and eighty-five species, one hundred and four 

 are distributed through the northern portion of both hemis- 

 pheres in high latitudes and at great altitudes.^ The botanist 



iGray and Hooker. " The Vegetation of the Rocky Mountain Region 

 and a Comparison with that of other Parts of the World," in Bull, U. S. 

 Geol. and Geog. Surv. Terr. VI. 1. 



