440 BOTANICAL GAZETTE [ DECEMBER 
the Macrospartinetum, are certain shrubs, Myrica Gale and Salix discolor, of 
which the former persists upon the floating bog. 
To this as to the following associations I have given but little 
study, and have little of value to offer upon them. It is an 
aggressive association, constantly tending to move up upon the 
broadleaf marsh, the transition to which is of the most gradual 
character. Of all the associations of the marshland, this has the 
least definite boundaries, and indeed there is some question as 
to whether it deserves distinct rank. 
IV. BOG FORMATION. 
Consists of plants capable of existence in stagnant but pure 
water, showing, unless immersed, marked xerophytic characters - 
(including reduction in size both of entire plant and of its parts) 
in adaptation to the lessened power of water-absorption by 
roots exposed to low temperatures. 
The bogs occupy the entire marsh country above the heads 
of the tide on the rivers, and also places between rivers where 
drainage is obstructed, but their area has been much reduced in 
the marsh country by artificial processes of conversion back to 
marsh (fig. 2 and p. 179). It includes three associations. 
8. THE CAREX-MENYANTHES, OR FLOQOATING-BOG ASSOCIATION, OR CARICETUM. 
By far the most extensive and characteristic bog association 
of the marshland, occupying the old marsh surface from near 
the head of tide on the marsh rivers to near the neighboring 
uplands (figs. 2,7). The transition from the Aspidetum to the 
typical Caricetum is perfectly gradual, so that it is difficult to 
place a limit between the two associations. The marsh, as earlier 
fully explained (p. 173 and fig. 4), falls away gradually from tide- 
head, so that leaving behind the high marsh with its Phleumetum 
we reach a somewhat wet marsh with its Macrospartinetum and 
a constantly wet marsh with its Aspidetum, and finally come to 
a marsh with constant standing water above the surface, and here 
begins the Caricetum. The characteristic dominant plants are 
sedges of several species whose copious interlacing air-storing 
rootstocks form a mat, which floats upon the surface of the water 
as it deepens (jig. 4), and which becomes three or four feet in 
