30 BOTANICAL GAZETTE [JANUARY 
pennsylvanica, P. pumila, Andropogon scoparius, A. jurcatus, Dan- 
thonia spicata, Lacinaria cylindracea, Salix humilis, Cladonia rangi- 
jerina, etc. This style comprises the worst part of what is called the 
“plains.” 
2. Lowland types. 
_ For the most part the swamps which were originally wooded have 
not been denuded of forest. Where they contained white pine, 
that was taken out, leaving the other trees, which protected the 
undergrowth and soon produced a dense, almost jungle-like formation. —_ 
Within the past few years the merchantable arbor vitae and tamarack 
have been removed from these swamps, but almost always enough 
small trees are left to produce shade. Also, the swamps have not 
been subjected to burning nearly so often as the uplands, and are 
generally in much more nearly. their original condition than are the 
latter. The three types may be described as follows: 
E. OPEN MEADOW TyPE. This is partly open hay meadow 
(largely of ‘“blue-joint,” Calamagrostis canadensis), partly ot bul- 
rush and cat-tail marsh, and partly of sphagnum bog. It grades 
into the other two types. : 
F. TAMARACK-ARBORVITAE swamp. This is the most typical 
swamp of the region. It contains Larix laricina, Thuja occidentalis, 
Picea canadensis, P. mariana, Abies balsamea, which form dense _ 
and often impassable thickets. In some localities Larix occupies 
almost all the ground to the exclusion of other trees, and in other 
places the same is true of Thuja. But there is not nearly so much ~ 
tendency here for these two trees to form separate and distinct 
types as is found cae south.'® There the tamarack seems t¢ — 
occupy ee portions of t p lands which are most poorly drained, 4 
the arbor vitae esinae in incailities where drainage is more thorough, 
yet still not complete enough for the river swamp vegetation. Here — | 
the question of drainage does not appear to play so important a part. ‘ 
G. Mrxep swamp. This formation is found near swamp Mar 
gins, especially where the underlying clay is near the surface. Thus | 
it often occurs along lines where the hardwood forest reaches dowr 
be Si bie tte ees ee 
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