352° BOTANICAL GAZETTE [NOVEMBER 
salt-enduring plant (halophyte) of the marshes, following every- 
where except on the newest marsh the margin of thesalt water, 
from the open sea, where it is stunted to 6 (15°™) or less in 
height, along the tidal rivers, where it forms on their sloping 
banks much below high-tide mark dense clumps of a few square 
feet in area (locally called ‘‘sedge-bogs”’), following the salt 
water through leaky sluices inside the dikes, and elsewhere in 
ditches behind the dikes, and reaching its perfection of size, 
some 3 to 4 * (1 to 1.30™) in the brackish water of the lakes in 
process of filling with new mud. It is the dominant and the 
only member of the association (Spartinetum) in which it occurs. 
This species is a very typical representative of an important 
Fic. 8.—Cross-section of the region represented in fig. 7, at the dotted line. 
vegetation-form. It consists of a system of perennial branching 
rootstocks running just beneath the surface, well sheathed by 
leaf bases, giving off extremely slender roots, protected by a 
fine-celled, thick epidermis and containing numerous large air 
passages, which, in connection with those of the leaves, explain 
the plant’s power to withstand prolonged immersion. From the 
rootstocks rise frequent short vertical stems, completely and tightly 
enwrapped and protected by the bases of the half dozen or more 
stiffy erect, more or less inrolled slender leaves, their sizes 
varying inversely with the degree of salt to which they are 
exposed. The leaves are smooth on the back, which is covered by 
a very small-celled, thickly cutinized epidermis supported by a 
collenchymatous and sclerenchymatous hypodermis, and is prob- 
ably quite impenetrable to water and gases; their inner face, 
however, is folded into deep grooves, at the bottoms of which lie 
few stomata, with the large water-storing cells near them. The 
mechanism appears to be such that the fulness of the latter cells 
holds the leaf flat, thus opening the grooves, giving the stomata 
free outlet to the atmosphere outside, but the withdrawal of 
