60 



tually favor a combination of spring and swamp formation, and 

 as a matter of fact there occur spring-swamp formations in the 

 higher levels of the slopes and swamp-spring formations in the 

 lower levels and in the bottom of gulfs and valleys. 



While on the whole bilateral zonation within the area under 

 discussion is extremely rare or practically absent, it is interesting 

 to observe how unilateral vertical zonation has established itself, 

 where conditions of water content as well as orientation and 

 inclination of slope, permit. Especially the slopes of Amster 

 Brook gulf as well as those of Dead Valley afford some striking 

 illustrations in this respect. (See Map.) 



Another very interesting feature that tends to illustrate the 

 bearing of the factor of the orientation of gulfs and valleys upon 

 the distribution of the vegetation, is met with in Dead Valley. 

 Where the carpet of the northern slope, exposed to moisture- 

 bearing southeast and east winds, is almost exclusively composed 

 of Ranunculus pennsylvaniais , while on the same level on the 

 opposite slope, facing the drier north and northwest winds, 

 Hieracium pilosella forms a close carpet. (See Map.) 



The following are the species that usually constitute the 

 plateau-gulf and valley formation : 



Abies halsamea 

 Acer Saccharum 

 Acer ruhrum 

 Agrimonia hirsuta 

 Alnus incana 

 Antennaria plantaginifolia 

 Apocynum androsaemifolium 

 Aquilega canadensis 

 Asclepias incarnata 

 Bidens connata 

 Melissa clinopodium 

 Cardamine hirsuta 

 Carex gynandra 

 Carex pauciflora 

 Carex trihuloides var. monili- 

 formis 



Caulophyllum tJialictroides 

 Cerastium nutans 

 Chelone glabra 



Chrysosplenium americanum 

 Circaea alpina 

 Clematis virginiana 

 Cynoglossum officinale 

 Epilobium angustifolium 

 Epilobium molle 

 Epilobium palustre 

 Erigeron strigosus 

 Eupatorium perfoliatum 

 Eupatorium purpureum 

 Fagus grandifolia 

 Fragaria canadensis 

 Fragaria virginiana 



