356 BOTANICAL GAZETTE [NOVEMBER 
we find the greatest variety of tree species, among which are Fagus 
atropur pureus, Quercus rubra, Ulmus americana, Platanus occidentalis, 
Acer saccharum, Tilia americana, Acer saccharinum, Fraxinus 
americana, Gleditsia triacanthos, Liriodendron tulipijera, Gymnocladus 
dioica, Cercis canadensis, Asimina triloba, and Celtis occidentalis. 
The clay morainic area is dominated by Quercus rubra, Q. alba, 
Q. velutina, Hicoria ovata, H. glabra, Acer rubrum, Ulmus americana, 
and Quercus macrocar pa. 
In the region of the interlobate moraine the disappearance of 
the more mesophytic forms is quite marked. The forest is there 
largely composed of Quercus coccinea, Q. macrocarpa, Q. velutina, 
Q. alba; and as we go northeastward these become associated with 
Pinus strobus. Quercus prinoides forms a characteristic shrubby 
growth along the roadsides and in waste places. 
Such is the forest background in which are set the thousands of 
acres of bog and swamp, and to which the groves of Larix laricina 
exhibit a marked contrast. These tamarack areas are to be seen 
on all sides in the region of the interlobate moraine; they are quite 
common in the clay morainic belt, but are practically wanting on the 
lake plain. 
As one follows along the morainic country from northern Indiana 
into the ‘“thumb”of Michigan, he passes from a region dominated 
by a rich mesophytic broad-leaved forest to one of conifer and xero- 
phytic broad-leaved ascendency; from a region whose low grounds 
are characterized by a swamp flora to one in whose depressions = 
bog flora reaches a high state of development. In this gost 
it is interesting to note that one finds this gradual change epito 
in the Huron valley as he goes from its mouth to its source. 
METEOROLOGICAL CONDITIONS. 
Under this head we shall consider the general meteorologies 
conditions of the Huron basin, and compare them with the meteo 
ological conditions found about the center of the distribution of oe 
plants (55, p. 406). In general, this center extends one's f 
Winnipeg through the upper Great Lake region down the ¥ ge 
the St. Lawrence to the Atlantic coast. It is in the coast aor 
however, that the bogs reach their highest development, eos 
