THE BOGS AND BOG FLORA OF THE HURON RIVER 
VALLEY. 
EDGAR NELSON TRANSEAU. 
(WITH SIXTEEN FIGURES) 
[Concluded from p. 448.] 
IV. The ecological characteristics of the bog flora and their causes. 
The plants occurring in the bog habitat are almost all perennials. 
In the case of the herbaceous vegetation, the winter is passed by 
means of subterranean rootstocks. The shrubs are in part evergreen 
and in part deciduous. The tamaracks and the two birches are 
deciduous, and the black spruce and pine are evergreen. 
Most of the herbaceous and shrubby forms multiply abundantly 
by vegetative shoots of one form or another. The length of the 
underground stems of the shrubs is proverbial, but is best appreciated 
by one who has attempted to dig up one of them entire. In con- 
nection with the competition between species for space in the habitat, 
this is of the greatest importance. A luxuriant growth of cassandra 
furnishes the most :favorable situation for the development of sphag- 
num in this vicinity. Its profuse branching affords a framework 
for the upbuilding of the sphagnous layer, its shade properties do not 
interfere with the photosynthetic work of the moss, and it protects 
‘it from the drying effects of wind and direct insolation. Where such 
associations occur, the difficulties presented for the germination for 
most seeds, and the efficiency with which competition is combated, 
are evidenced by the fact that among the tree species only the tama- 
rack, spruce, and pine are successful invaders. All of these plants 
send out adventitious roots from the stems and branches, and so keep 
pace with the upward development of the moss. The absence of 
poplars, willows, red maples, and elms in such undisturbed situations 
must be in part attributed to the completeness with which such terri- 
tory is controlled by the cassandra-sphagnum association. 
ECOLOGICAL ANATOMY. 
Aside from the purely aquatic forms which have received much 
Botanical Gazette, vol. 41-] [17 
