DOCKS AND SORRELS OF ESSEX
265
DOCKS AND SORRELS OF ESSEX
BY J. EDWARD LOUSLEY
[Read 25 February 1950]
DOCKS and Sorrels are not a popular group and in fact it is
probably true to say that more study is devoted to planning
their destruction than to any other feature. Nevertheless, their life-
histories present many interesting features and some of the species
are not without beauty. As they are not particularly difficult to
identify their neglect by so many amateur botanists is quite un-
warranted.
Docks and Sorrels together make up the genus Rumex, a group
of world-wide distribution. The commonest and most widely dis-
persed Docks are agricultural pests and as such are carried from
country to country as impurities in agricultural seed and produce.
Some foreign species brought in this way have become established
on rubbish dumps, such as those at Dagenham and Grays, or on
quay-sides as at Colchester. In addition to these agricultural pests
we have native Docks which are water-loving plants growing by
ponds, dykes, and rivers and in shingle slacks. Sorrels are just as
troublesome to the farmer as some of the Docks—and for the
same reason. Their foliage takes up valuable space which reduces
the amount of good herbage or other crops.
Nearly all the Docks and Sorrels which have been found in
Britain are perennials though some of them can produce fruit
within the first year of their life. The shape of the leaves is a useful
character in distinguishing the various species but that of the
valves is even more helpful. These are the three outer perianth
segments which enlarge after the flowers have been fertilised so
that they envelope and protect the fruit by the time this is mature.
In some species they have entire margins, in others they are
toothed; some are pointed, others blunt; some broad, in other
species they are long and narrow. Sometimes they carry spherical
or ovoid structures which are filled with corky cells with big air
spaces and are known as tubercles. These serve as floats and like
other variations in the valves are connected with the dispersal of
the fruits—in this case by water carriage.
Since the valves provide by far the best and easiest characters
for distinguishing Rumex species it is advisable to collect only
material in good fruit until you feel confident that you know them
well enough to try to identify them in a less mature state. With a
good fruiting panicle, and the lowest undecayed leaf available,
there is usually little difficulty in identification. Most beginners
ignore this simple rule and puzzle over immature material which
creates unnecessary difficulties. Of course it is possible to name
most of the species when young—I can distinguish most of the