371 



Hyclrophyllum appendiculatum. 

 Hydrophyllum virginianum. 

 Ariserna cftphylla. 

 Trillium grandiflorum. 

 Trillium eernuum. 

 *Trientalis amerieana. 

 *Maianthomum eanadense. 

 Senecio aureus. 

 Botrychium virginianum. 

 Osmunda regalis. 

 Osmunda einnamomea. . 

 Pteris aquilina. 

 Cystopteris fragilis. 

 Aspidium spinulosum. 

 Aspidium eristatum. 

 Aspidium thelypteris. 

 Adiantum pedatum. 

 Anoclea sensibilis. 

 Camptosorus rhizophyllus. 

 Asplenium aerostieoides. 

 *Lyeopodium lueididum. 



On the west side of the arbor vitae association is an almost undisturbed 

 tree association, differing greatly in composition from that just described. 

 The arbor vitae zone is made up largely of plants of northern origin or plants 

 characteristic of bogs, while the plants of the other group, called the maple- 

 tulip association, are those typical of the climax mesophytic forest of the 

 region and are distinctly southern in their origin. A comparison of the 

 distribution of the more distinctly boreal forms of the arbor vitae assoeia- 

 tiln, indicated thus (*) in the list, with those given below Tor the maple- 

 tulip association, will make the difference in origin very striking. Practically 

 all these boreal forms occur outside the limits of distribution given by the 

 best manuals. The beech is usually a member of the climax mesophytic 

 forest of this region, but since for some reason it is absent from all the forests 

 of this vicinity for several miles around, it is also absent in the bog. The 

 principal trees of the maple-tulip association follow: 



