1912] Sinnott,— Pond Flora of Cape Cod 27 
from the water’s edge. In ponds with absolutely no outlet, the rise 
and fall of the water is greatest, and the beach here is of considerable 
width, but in many cases the pond overflows into a drainage-brook 
at a little above its normal summer height and is consequently sur- 
rounded at that season by only a narrow belt of sandy shore. This 
is the case with most of the large lakes. 
The character and extent of the vegetation on these beaches and 
in the shallow water at the pond-edge vary considerably from one 
pond to another and seem to be under the control of several different 
factors. 
Small ponds, in general, show a much more luxuriant plant-growth 
around their shores than do larger ones, which are apt to have long 
stretches of pure sand or gravel beach and bottom, practically devoid 
of vegetation. This may well be explained by the fact that the wave- 
action, which is much more vigorous on extensive sheets of water than 
on smaller ones, has in these larger ponds pretty thoroughly washed 
out all the mud and fine material in the sand, and left it in much the 
condition of a barren sea-beach. It is also conceivable that in the 
winter and spring, when the water is usually highest and storms are 
most frequent, the waves should wash out and destroy seeds and young 
plants which had found lodgment along the shore. It is noticeable 
that wherever the soil next the shore has been disturbed and broken 
up, as by a cutting or a road, the waves have spread the sand up and 
down the beach for a considerable distance, to the practical exclusion 
of all vegetation. These same sterile sandy beaches are also occa- 
sionally found on small ponds, but in such cases a good depth of water 
and an abruptly sloping bottom are always observable. Wherever 
conditions are favorable, therefore, for washing out fine material of 
all kinds from the shores and depositing on the bottom, a sterile 
beach of pure sand and gravel will result. 
Most of the smaller ponds, which are protected by their size from 
violent wave action, have bottoms sloping gently to no great depth 
and consequently both the beaches and the shallow shores are well 
able to support a considerable vegetation. 
It is also noticeable that on the same pond such portions of the 
shoreline as are most exposed to the waves or which have especially 
steep slopes are much less thickly covered with plants than are the 
protected stretches, and that the coves or sheltered places always 
show a more luxuriant vegetation than do the open straight beaches. 
