338
THE ESSEX NATURALIST
the occurrence of other plants along Thameside, more particularly on the
rubbish dumps farther downstream. My hopes in this direction, however,
were not realised, although we did find some unusual plants.
The reddish bog ore is very moist, and after the driest summer we have
had for some years it was a treat to find a spot with an abundance of green
plants obviously rejoicing in the damp conditions. Most of the plants on
this ore called to mind the plants of the London bombed sites, and they
included the Oxford Ragwort (Senecio squalidus), Sticky Ragwort (S.
viscosus), Fireweed (Chamaenerion angustifolium), Eastern Rocket (Sisym-
brium orientale), Melilot (Melilotus altissima) and Mignonette (Reseda
lutea), together with masses of Persicary (Polygonum Persicaria). My view
of the bog ore as a habitat is much the same as of the bombed sites and
similar open spaces. Simply, it is an open habitat ready made for
colonization by any species which has the means of speedily invading the
area and establishing itself. If the working conditions of this site per-
mitted, it would be an interesting study to leave a small area to see what
happened as the invaders came into competition with the slower-growing
but more permanent members of the flora of the area who would possibly
take over this site—subject to their soil requirements—and eventually
dominate it.
The heap of synthetic ore called Manox, although equally moist, was by
no means so floriferous, and its plants were chiefly Polygonums, including
P. persicaria, P. aviculare, P. convolvulus and the alien P. cuspidatum.
Apart from two species of grass, the only other plants were one specimen
each of the Great Plantain (Plantago major) and Black Nightshade
(Solanum nigrum).
The next area we visited was the old cricket pitch, which was well supplied
with plants of Chicory and an abundance of the alien spurge Euphorbia
virgata. In using this name I do so bearing in mind that the taxonomy
of this and closely-related species is in some confusion, and it may even-
tually prove that there are several species involved. This spurge is one
that is extending its range in Britain and it occurs in many places in
Essex. On the same area were some excellent plants of the Greater Knap-
weed (Centaurea scabiosa), the rather less common Crown Vetch (Coronilla
varia) and an old friend of our Club—Bunias orientalis. This plant is known
to members from the old chalk pit at Grays, where it has now been estab-
lished for over thirty years. It is a native of south-east Europe and has
spread as a weed of roadsides over the greater part of the Continent. In
England it occurs on rubbish dumps and on similar situations. The Crown
Vetch is described as a native of woods and dry limestone hills, but in
England it is much more often found as a casual of waste ground, which
description fits the plant in this locality to a "T".
The banks of the River Lea, which is here tidal, were equally fascinating.
The first plant we spotted growing on the revetment of the railway bridge
was the Hemlock Water Dropwort (Oenanthe crocata), extremely poisonous
in all its parts. We also found the Larger Bindweed (Calystegia
sylvestris), Coltsfoot (Tussilago farfara) and Michaelmas Daisy (Aster sp.),
the last probably carried to the spot by the tidal waters. Various salt-marsh
plants such as the Sea Aster (Alter tripolium), Sea Beet (Beta maritima)
and Sea Matricaria (Matricaria maritima ssp. maritima) occur beside the
river, together with some gigantic plants of the Yellow Flag (Iris pseuda-
corus) and a small patch of John-go-to-bed-at-noon (Tragopogon pratensis).
The most striking plant of the riverside area was the abundance of the
Angelica (Angelica archangelica). Miss Cr. Lister (1936) visited this area
and in a paper in The Essex Naturalist gave a vivid description of this
plant and the characters to assist in its identification. Since refreshing