106 



the Alleghany plateau in Pennsylvania; the giant redwoods of 

 the California coast region, which seem to be almost exempt from 

 fire and snow; and the open sunny yellow pine forests of the Sierra 

 Nevada and central Arizona, with frequently burned grassy under- 

 growth similar in aspect to that of the southeastern pine-barrens. 

 In the description of this type of forest there is no mention of the 

 genus Picea, which is a very conspicuous element both in Maine 

 and in the Rocky Mountains; and the white pine and hemlock, 

 noted as characteristic, perhaps belong more properly to the 

 "northeastern evergreen-deciduous transition forest." 



"Swamps and marshes" is another diverse aggregation, in- 

 cluding as it does the alluvial bottoms of the Mississippi and a 

 few other rivers, with dense deciduous forests, the non-alluvial 

 Dismal and Okefinokee Swamps, the treeless Everglades, and the 

 salt marshes of the coast. 



The alpine summits of New England and New York, as well 

 as of Mt. Shasta, are not shov/n, probably because too small in 

 area. 



With the few exceptions here noted, the map gives an excellent 

 bird's-eye view of the original vegetation of the United States. 

 If it is compared with the latest geological, physiographic, and 

 climatic maps of the same area many interesting correlations 

 will be noted. It is to be hoped that other botanists who see 

 Dr. Shreve's map will be stimulated to map their respective 

 states or similar areas in a somewhat similar but more detailed 

 manner. Perhaps in the not distant future it will be possible to 

 employ statistical methods that will almost eliminate the personal 

 equation; for example, to divide the country into natural geo- 

 graphical divisions* (based on soil, topograph}', climate, and all 

 other significant factors), determine the relative abundance of 

 the trees (or other plants where there are few or no trees) in 

 each, and put on the map in order of abundance the names of 

 enough to make up say 50 per cent, or better 75 per cent, of the 

 total in each region. There will always be some difference of 



* For a few recent maps of the United States or parts thereof that will serve 

 pretty well for outlining the geographical divisions see Bowman's Forest Physiog- 

 raphy, 191 1, Hawley & Hawes's Forestry in New England, 191 2, and N. M. Fenne- 

 man in Annals Assoc. Am. Geographers, Vol. 6, 10 17. 



