102 



may be recognized. Reference has already been made to the 

 southeastern center. Similarly the southwestern section may be 

 looked upon as including the usual route along which northbound 

 immigrants from the south today invade the state. It is in this 

 area that Melanihium latifolium, Liquidambar Styraciflua, Pyrus 

 arbutifolia, Viburnum prunifolium, Crotonopsis linearis, Oenothera 

 longipedicellata, and Cacalia suaveolens reach their northern limit 

 in the east; while many other species, such as Wolffia Columbiana, 

 Aristolochia Serpentaria, Cimicifuga racemosa, Heuchera amer- 

 icana, Rubus cicneifolius, and Ilysanthes anagallidea, which extend 

 locally into other parts of Connecticut, are frequent or common 

 here. Northwestern Connecticut, on the other hand, constitutes 

 a natural center of distribution for boreal species. Mention has 

 already been made of the nature of the climax forest in this region. 

 The swamps, likewise, are suggestive of the north; for here, as 

 nowhere else in the state, tamarack swamps are of frequent 

 occurrence; while the spruce, elsewhere represented by dwarfed, 

 scattered specimens, becomes in the bogs of northern Litchfield 

 County a tree of goodly proportions, and in at least one locality 

 forms a forest of appreciable extent. Furthermore, on the nor- 

 thern slopes of some of the higher mountains in this section 

 spruces fifteen or more meters in height are sometimes found 

 growing as upland mesophytes. The balsam fir {Abies balsamea) 

 and arbor vitae {Thuja occidentalis) are also native at several 

 stations in northwestern Connecticut. Altogether no less than 

 90 species of plants have been recorded only from this part of the 

 state, and of these fully 30 per cent, reach here their southern- 

 most limit of range in the east.^ In the subjoined list are given 

 a few of the seed plants which are apparently restricted to this 

 area. 



Cinna latifolia Mitella nuda 



Carex Bebhii Ribes prostratum 



Carex pauciflora Potentilla tridentata 



Carex paupercula Dalibarda repens 



Streptopus amplexifolius Viola nephrophylla 



1 This estimate also includes some species which range farther south along the 

 Alleghanies. 



