MARYLAND WEATHER SERVICE 291 



Bogs and characteristic of them are far less common, if not absent, 

 smith of the glaciated region. But few of these, indeed, are found 

 in the Bogs of the Mountain Zone, — a less number than are found 

 in the bogs of the "Western Shore district of the Coastal Zone. 



The characteristic species in the Bogs of Garrett County which 

 arc also abundant in bogs in the glaciated portion of North America 

 are: Eriophorum viir/iniciun . Bub us hispidus, Oxy coccus macro- 

 carpus, Drosera rotundifolia, Dryopteris (helypteris, Habenaria 

 clavellata, Triadenum virginicum, Dulichium arundinaceum and 

 Osmunda regalis. 



These shrubs characteristics of the Bogs are Alnus rugosa, Alnus 

 incana, Ilicioides mucronaia. Ilex verticillata, Azalea viscosa and 

 Hypericum densiflorum. Oilier herbaceous species are Solidago 

 monticola. Gentiana linearis, Scirpus cyperinus, Carex atlantica, 

 Dryopteris cristata, Carex baileyi, Oaltha palustris, Hypericum 

 canadense, Dryopteris spinulosa and Pogonia ophioglossoides. 



Conclusions. 



The floristic history of tin- Mountain Zone has been similar to 

 that of the Midland. There have been climatic fluctuations since 

 Tertiary time that were of the same amplitude as those to which the 

 Midland District was subjected but their maximal and minimal 

 points were lower. This has resulted in a less invasion of the Moun- 

 tain Zone by southern forms, and the persistence of numerous 

 northern forms. 



Although the main outlines of the topography of the Mountain 

 /••nc are old and topographic development has gone on well toward 

 maturity in many localities, yet the elevation and the differential 

 weathering of the underlying rocks has prevented a maturing of the 

 topography of the Zone as a whole. The presence of the great moun- 

 tain ridges and of the long valleys with horizontal floors has main- 

 tained a diversity in the vegetation far greater than that of the 

 Lower Midland District. 



In the relatively level valleys the influence of the physical char- 

 acter of the underlying rock is shown through its determination of 

 the character of the soil, while in all other situations topography 



