228 Rhodora [DECEMBER 
The non-halophilous vegetation of the fresh part of the bog may be 
somewhat arbitrarily divided into two zones at the point where Chamae- 
cyparis drops out of the flora. The zonation here appears to be due 
to the increasing quantity of salt in the bog water as high tide level is 
approached. ‘The flora of the landward zone is essentially of the 
same composition as in those Chamaecyparis bogs of the region which 
are not open to the direct influence of the sea. Since certain of its 
species are more sensitive to the action of salt than others, they drop 
out of the flora at varying distances seaward. ‘That portion of the 
fresh part of the bog between the Chamaecyparis zone and the transi- 
tion zone is composed of certain relicts from the flora of the Chamae- 
cyparis bog, together with invaders from other fresh water habitats. 
1 
The sketch map shows the six zones, designated, in order from 
the sea landward, A, B, C, D, E, and F. Plants which belong prop- 
erly to none of these zones occur in standing water of the marginal 
fosse, — a well marked topographical feature in the fresh part of the 
bog, which is by no means obliterated in the upper part of the salt 
marsh. 
In the following lists it has been convenient to group the plants of 
some of the zones according to manner of growth, as, for example, 
those of zone F into trees, shrubs, herbs and mosses. Where this has 
