402 



George E. NicJioIs, 



Lichens 



Cladonia alpestris 

 Cladonia sylvatica 



Cladonia rangiferina 

 Cetraria islandica 



Bryophytes 



Sphagnum capillaceiim tenellnm Lcucohrymn glaiiciim 



S phagnum tcnerum Racomitrnim lanuginosum 



Ptilidium ciliare Hypniim Schreheri 



Vascular Plants 



Pteris aqnilina 



Abies balsamca 



Picea niariana 



Larix laricina 



Juniperus communis montana 



Maianthcmiim canadense 



Myrica Gale 



Pyrus melanocarpa 



Amelanchier sp. 



Empetrum nigrum 



Ncmopanthus mucronata 



Cornns canadensis 

 Andromeda glaucophylla 

 Chamaedaphne calyculata 

 Epigaea rep ens 

 Kalmia angustifolia 

 Kalmia polifolia 

 Ledum groenlandicum 

 Rhododendron canadense 

 Vaccinium canadense 

 Vaccinium pennsylvanicum 

 Viburnum cassinoides 



Any of the other species mentioned earlier as characteristic of 

 sedge-grass heath may grow here also, but these, for the most 

 part, are confined to the depressions between the hummocks. 



The structure of the hummocks (Fig. 53) is extremely inter- 

 esting. Examination shows them to be due entirely to plant 

 activity. Internally they consist of an intricate mass of incom- 

 pletely decomposed vegetable debris : the sort of structure com- 

 monly referred to as "raw humus." Ordinarily the bulk of the 

 material has been derived from the lichens and from the leaves 

 of the various shrubs which inhabit the surface of the hummock, 

 the whole being bound together by the stems and roots of the 

 surface vegetation. In some cases the sphagnum has contrib- 

 uted very largely to the formation of the hummocks : in one 

 instance the excavation of a hummock two feet high, whose sur- 

 face vegetation, aside from various shrubs, consisted entirely of 

 Sphagnum capillaceum tenellum, showed the whole hummock to 

 have been built up by this moss, whose remains, still in a fine 



