SEED PLANTS OF UPPER LITTORAL BELT 717 
The soil on which S. patens grows at the west end of the Spit is, at its lower 
margin, a compact, peat-like, saturated mud, having a depth of from 14 to 24 
inches. At the upper margin the soil bearing the sparser stand of S. patens 
becomes drier, more sandy, and much thinner, often only 6 or 8 inches deep 
between the 7.5 and 8 foot levels. 
Spartina patens on the steeper shores of the harbor: The short, narrow strips 
of S. patens found about the harbor are few and scattered on the east and west 
sides, but more numerous on the eastern half of the Spit. On the east side, 
for example, there are small patches of the grass on the wharf at 950 north, and 
still smaller ones, in which some 8S. glabra is found, on the elevated areas 
between the fresh-water streamlets on the east side of the Marsh, between 0 and 
200 north (see plates x1 and x111). More considerable areas of nearly pure 
S. patens are found on the projecting points of the shore at 200 north and 300 
north. On the west shore there are short strips of this grass at 790 to 930 north 
and at 1,010 to 1,040 north; a broad strip at 1,650 to 1,725 north; a short, 
narrow strip on elevated soil completely surrounded by S. glabra, at 1,750 to 
1,765 north. Beyond this are found but two very small patches at 1,825 north 
and 2,000 north (plate x111). The only stands of the grass on these two shores 
are at the points mentioned. 
On the south shore of the Spit, as we have intimated above, the continuous 
band of Spartina patens found in the northwest corner of the harbor does not 
reach eastward beyond 590 west. East of this we find S. patens in isolated strips 
from 10 to 100 feet long. These strips of nearly pure S. patens may occupy the 
whole width of the upper littoral beach between the S. glabra and the 7.5-foot 
level, e. g., at 280 to 390 east, 530 to 560 east, 675 to 730 east, and at 830 east. 
At other points, however (plate virB), the 8S. Patens may form rather narrow 
and short patches of pure S. patens, very nearly surrounded by the Sueda or 
Salicornia europea, which at these places form the dominant plants in the cover- 
ing of the upper httoral beach, e. g., at 250 west and at 430 to 450 west. At still 
other points the Spartina may occur scattered rather evenly through the dom1- 
nant Sueda or Salicorma europea, e. g., at 370 to 480 west and at 390 to 530 
— east. (See plate v.) 
The conditions affecting the distribution of S. patens are suggested by what 
we have said above of that distribution. It is evident that this grass can grow 
on either peat or mud, or even on sandy soil, between the 6 and 8 foot levels, if 
the soil is not flooded by salt water longer than 5 or 6 hours per day, and is not 
saturated by fresh water. How far each of these various factors works directly 
and how far indirectly has not been determined definitely in the only way it can 
be, namely, by experiment. It seems probable, however, from a study of the 
occurrence of this plant and its competitors, that it does not dominate on soils 
saturated by fresh water because it does not endure fresh water as well as its 
competitors, and therefore is driven out by them. That it will endure some 
fresh water in and above the soil seems evident from the fact that S. patens is 
found beside the fresh-water streamlets on the east side of the Marsh. 
The lower limit of S. patens is probably determined chiefly by the competi- 
tion of S. glabra, since in a few places where the latter is absent the S. patens 
goes down to the 6-foot level, and at 200 north on the east shore to the 5.5-foot 
level. Practically everywhere about the harbor S. glabra occupies the next 
lower belt, and it is evidently the unfavorable physical conditions for this latter 
