SURVEY AND COMPARISON 171
of Juncus Gerardi are found. At the corners, Puccinellia
distans roots on the banks and spreads its stems some dis-
tance out over the surface of the water. Triglochin
maritimum is present in one place, and Spergularia mar-
ginata also occurs on the banks and where small drainage
channels from the field join the creek. In this part the soil
round the roots of Aster Tripolium has a chloride content of
.027 grams per gram soil (2.7 per cent). In the water here,
great masses of Ruppia maritima L., which in some places
extend right across the creek, are found. At 3C, where the
western bank is low and is covered by saline water in winter,
there is a patch of Hordeum marinum.
From 3C to 3A, the western bank is very low-lying, and
an area of wet, marshy ground extends from the creek
margin for about 10 yards inland. The distribution of species
in this region is illustrated by Plate 6, Fig. b. Scirpus
maritimus and Juncus Gerardi line the creek margin, and
behind these a considerable area of Puccinellietum has been
developed. Both P. maritima and P. distans are represented
here. Aster Tripolium is also frequent, and a few plants
of Suaeda and Salicornia sp. occur. Inland from the
Puccinellietum, a bank of Agropyron pungens about two
yards wide separates the marshy ground from the ploughed
land. In this part of the creek the Ruppia is less persistent.
Creek 7 has not been allowed to retain its original shape
near its junction with Creek 4, but for the remainder of its
length it winds between the fields in the same way as Creek
3. Near the junction of Creeks 4 and 7, the whole of the
ground is marshy, and where it is wettest, and in the channel
of Creek 7 itself, Scirpus maritimus is dominant. In a large
area surrounding this, where the mud is exposed and
trampled and very soft, Puccinellia distans and Puccinellia
fasciculata (Torr.) Bicknell, Spergularia salina J. & C.
Presl., Suaeda and Salicornia Smithiana are found.
Chenopodium botryodes Sm. is also present here, and forms
several large patches. Raised parts of the ground are
colonised by Agropyron and Juncus Gerardi and some
Atriplex hastata. In one part of Creek 7, near the sea wall,
where the banks are raised and the water is deepest,
Phragmites communis is dominant.