DOCKS AND SORRELS OF ESSEX 269
Wennington, v.-c. 18, look very different from those of places
fully exposed to the sun.
9. R. sanguineus L. Native. The typical species described by
Linnaeus with purple veins to the leaves is very rare and I have not
seen material from Essex. The variety with green veins on the
leaves (var. viridis Sibthorp), the Green-veined Dock, is well
distributed, and perhaps even common, throughout the county.
Normally it is a woodland plant with pale thin leaves but there is
also a sun form which is often confused with R. conglomeratus.
10. R. Hydrolapathum Huds. Native. Great Water-Dock.
Common by dykes in the Thames and coastal marshes and by
rivers and streams inland in both vice-counties. A handsome plant.
11. R. obtusifolius L. Usually regarded as native but probably
an ancient introduction. Broad-leaved Dock. Grows round farm
buildings, in corners of fields, on roadsides and rubbish-dumps,
and is far too common throughout both vice-counties. This is the
least attractive of all British Docks and its coarse, often dust-
covered, leaves have no merit except as a popular remedy for
nettle stings.
It has become an agricultural and horticultural pest for the
same reasons as R. crispus but is more definitely perennial than
that species. I have never seen it growing in any place where I
could feel completely confident that it was native. Although proof
is lacking, the evidence suggests that it may have been introduced
into Britain from Europe many years ago and spread through the
country as a pest, just as it has in parts of the Southern Hemis-
phere in recent times. Three subspecies occur in this country
which differ in the characters described and illustrated in an
earlier paper (B.E.C. 1938 Rep., 123-8, 1939). Of these only the
common ssp. agrestis (Fries) Danser has been recorded from Essex
but the adventive ssp. transiens (Simonkai) Rech.f. and ssp.
sylvestris (Wallr.) Rech. have been collected in nearby counties
and should be looked for round docks and on rubbish dumps.
12. R. pulcher L. Native. Fiddle Dock. Local. I have recently
seen this at East Tilbury, v.-c. 18 and St. Osyth, v.-c. 19. The
species favours dry well-drained places and although widely
distributed in the county it is more plentiful near the sea, and in-
land evinces an unexplained partiality for churchyards. Village
greens and sandy commons are frequent habitats in other coun-
ties and it should be looked for in such places in Essex. Only the
native ssp. eu-pulcher Rech.f. has been observed but there are
other subspecies found as aliens in Britain (B.E.C. 1938 Rep.,
136-9) which might well occur.
13. R. obovatus Danser. Alien. This species is a native of Argen-
tine and Paraguay but is better known as an adventive in Scan-
dinavia, Germany, Holland, France, and Italy. In Britain it has