Forest Development in the Adirondacks 41 
Below this zone the dead sphagnum becomes more and more 
disintegrated, retaining, however, for a time its lighter color 
and spongy texture. Beneath this is the newer layer of brown 
fibrous peat which at greater depth becomes more or less decom- 
posed, taking on a blacker mucklike character in situations 
where periodic lowering of the water table permits better aera- 
tion during part of the growing season. Over the greater part 
of the area here considered, tall growing sphagnums, such as 
S. recurvum and S. magellanicum, form the living carpet, so 
that this living layer may be as much as five or six inches 
thick. The layer of dead but not disintegrated sphagnum is 
often of equal thickness. These two layers, together with the 
upper stratum of newly forming peat, constitute the medium 
in which the actively absorbing roots of vascular plants develop. 
In no case, even in parts of the marsh where the peat bed is 
very shallow, e. g., parts of the sedge meadow, have the roots 
of bog species been observed to penetrate the underlying sand. 
‘As previously mentioned, this substratum of living and dead 
sphagnum offers a medium in which vigorous development of 
both root and shoot organs is stimulated. In the sedge meadow, 
Carex oligosperma by vegetative propagation forms an almost 
exclusive community, binding the substratum into a close, com- 
pact sod. Fig. 6. Without exception the bog shrubs spread 
rapidly by vegetative means. This may occur as for example 
in Vaccinum augustifolium by normally subterranean rhizomes, 
but also as in Cassandra and black spruce as a result of vigorous 
root development from normally erect or leafy shoots, where 
the stem back of the newly formed roots ceases to grow and, 
becoming atrophied or dead, leaves the newly rooted branch 
as an independent plant. As a matter of fact, these old 
stems, though probably functionless, persist for an indefinite 
period, so that the result of vegetative propagation is to create 
expanding colonies of each species and thus brings about the 
spot wise occurrence of these associates in the bog shrub zone. 
Thus it will be noted that the conditions created by sphag- 
num as a growth substratum result in phenomena of vegetative 
propagation as noteworthy as in the case of submerged vege- 
tation of shallow lakes and ponds. 
