DISTRIBUTION OF VEGETATION IN UNITED STATES. 69 



through the forested portions of the western United States from the 

 Canadian boundary to Mexico. Pinus contorta is very nearly coin- 

 cident in its range with the northern portion of the area occupied by 

 Pinus ponder osa. Pinus edulis is used as an example of the type of 

 evergreen needle-leaved trees which is dominant in the Western Xero- 

 phytic Evergreen Forest. It has not been possible from any data 

 which are at hand to represent the range of this tree in as great detail 

 as we used for the other members of this group. 



3. Southeastern Evergreen Needle-Leaved Trees. (Plate 6.) 



Pinus palustris Mill. 



Pinus taeda L. 



Pinus echinata Mill. ( = P. mitis Michx.). 



Pinus caribaea Morelet ( = P. heterophylla (Ell.) Sudw.). 



The range of the members of this group of characteristic evergreen 

 needle-leaved trees of the Southeastern Mesophytic Forest has already 

 been discussed on a previous page. 



4. Northeastern Evergreen Needle-Leaved Trees. (Plates 7 and 13.) 



Pinus strobus L. 



Tsuga canadensis (L.) Carr. 



Pinus virginiana Mill. ( = P. inops Ait.). 



Pinus divaricata (Ait.) DuMont. ( = P. banksiana Lamb.). 



Abies balsamea (L.) Mill. 



The distribution of four of these species has also been discussed in 

 showing the relation of their ranges to the range of the eastern portion 

 of the Northern Mesophytic Evergreen Forest. Pinus virginiana has 

 been used as an example of a type of distribution which is somewhat 

 unusual among the evergreen needle-leaved trees, occupying an area 

 between the northern and southern areas of evergreen needle-leaved 

 forest and lying almost wholly in the deciduous region. 



5. Eastern Deciduous Trees. (Plates 16 and 17.) 



Quercus alba L. 



Fagus atropunicea Ehrh. ( = F. americana Sweet =F. ferruginea Ait.). 

 Castanea dentata (Marsh.) Borkh. ( = C. sativa var. americana Sarg.). 

 Acer saccharum Marsh. (=A. saccharinum Wang.). 



This group comprises four of the commonest trees of the deciduous 

 forest, all of which were used in the map of cumulative occurrence of 

 trees of this type given in plate 6. Quercus alba is found practically 

 throughout the eastern half of the United States, with the exception 

 of peninsular Florida and northern Michigan and Minnesota. Fagus 

 atropunicea is also found throughout the greater part of the eastern 

 United States, although it is somewhat less restricted in range than 

 Quercus alba. Castanea dentata is more strictly confined in its occur- 

 rence to the Alleghenian region and its adjacent areas. Acer sac- 

 charum is similar in its range to Quercus alba, but extends farther to the 

 north and not quite so far to the south. 



