26 Rhodora [FEBRUARY 
from which streams are continuously flowing; and those which have 
poor drainage or none at all. To the latter group belong the great 
majority of the small ponds as well as most of the larger ones. 
The vegetation along the shores of the well-drained ponds is not 
distinctive and is very much like that found in similar situations 
throughout southeastern New England, save that it is somewhat less 
luxuriant. Wide sandy shores are, of course, absent. Where the 
bottom shelves off deeply and the banks are at all precipitous, the pine 
and oak flora of the barrens comes down to the water’s edge and the 
sandy or pebbly bottom near the shore will support only such plants 
as Nymphoides lacunosum, Lobelia Dortmanna and Scirpus americanus. 
In the majority of cases, however, the slope of the shore-line is much 
more gradual, and allows the accumulation of a considerable deposit 
of mud and silt, which forms a congenial habitat for a large group of 
plants, of which Pontederia cordata and Decodon verticellatus are per- 
haps the most characteristic. These are found along the shores of 
all ponds whose water-level is approximately stable, and with them 
are such familiar things as Typha latifolia, T. angustifolia, Spar- 
ganium americanum var. androcladum, Sagittaria latifolia, Scirpus 
validus, Acorus Calamus, Impatiens biflora, Ludvigia palustris, Ascle- 
pias incarnata var. pulchra, Bidens connata and very many others, 
which form the dense and (for the Cape) luxuriant vegetation of 
such pond-shores. In the water flourish Castalia odorata, Nymphaea 
advena, Myriophyllum humile, various species of Potamogeton, notably 
P. Robbinsii, and other equally familiar plants. This general group 
of mud-loving things, particularly Sparganium americanum var. 
androcladum and Sagittaria latifolia are also characteristic of cran- 
berry-bog ditches and sloughs wherever alluvial mud has been de- 
posited. This whole mud flora is practically identical with that 
of similar situations throughout southeastern New England but com- 
prises a very different group of plants from those growing on the 
peaty mud of the undrained ponds in the sand-barrens. 
The ponds where drainage is incomplete or absent constitute the 
great majority of all the bodies of water on Cape Cod, and have associ- 
ated with them a large and distinctive flora. The water-level here 
is subject to great fluctuations, and the surrounding dry-ground vege- 
tation is consequently forced to stop at the extreme high-water mark, 
with the result that in the summer months, when all the ponds are apt 
to be rather low, a sandy beach extends for some distance upwards 
