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a specimen which turned out to be Marsh Yellow
Cress (Rorippa islandica). The banks of the
River Lea were the habitat of some unusual plants.
Another yellow Crucifer was the object of
considerable interest. Its fruits were
irregularly ovoid with warty projections. It
was an alien which is rare in Essex, called
the Warty Cabbage (Bunias orientalis). Nearby
were some impressive plants of Garden Angelica
(Angelica archangelica). The inflorescences
were dry at this time of year and rounded in
appearance, but the leaf shape and greenish stems
separated it from the Wild Angelica. Another
rare Essex Umbellifer grew here too. This was
Hemlock Water Dropwort (Oenanthe crocata).
This very poisonous plant could be recognised
by the shape of its fruits and leaves. Also
in this short stretch of river bank was Danewort
or Dwarf Elder (Sambucus ebulus). This shrub
is a native plant which is rare in Essex. Its
name either refers to its reputation of growing
from the blood of Danes or to the fact that it
can cause the "danes", or diarrhoea. The site
also gave us the opportunity to compare the
aromatic Wormwood (Artemisia absinthium) with
its very common relation Mugwort (Artemisia
vulgaris) .
After lunch, spent watching some inexperienced
barge handlers trying to enter a lock from
downstream by filling it up first, we spent the
afternoon exploring the land along the line of a
sewer which crosses the river. Again some
unusual yellow Crucifers attracted our attention.
The Tall Rocket (Sisymbrium altissimum) could
be compared with the common Hedge Mustard
(Sisymbrium officinale) by its long spreading
fruits and leaves with linear segments. The
Hoary Mustard (Hirschfeldia incana) creates
some difficulty to identify using CTW's key
because the veins in the valves are not obvious