268 THE ESSEX NATURALIST
Europe and the adjoining parts of Asia. In this country it is one of
the earliest Docks to flower, and grows to a height of nearly six
feet. The valves when just mature in June are often flushed with
red or green and are extremely handsome. Two of the subspecies
have been found in Essex:
ssp. eu-Patientia Rech.f. Valves 6-8 mm. long by 5-7 mm.
broad, often reddish, as is also the stem. Thoroughly established
at Dagenham, v.-c. 18, for over twenty years (e.g., Hubbard,
Summerhayes, and Turrill, 1929 in Hb. Kew).
In addition, this subspecies was established at Virley, v.-c. 19,
from about 1909 to 1921 (B.E.C. 1938 Rep., 145-6, 1939).
ssp. orientalis (Bernh.) Danser. Valves 6-8 mm. by 8-10 mm.
In 1938 this formed great thickets by the Thames between Grays
Thurrock and Tilbury, v.-c. 18 (Lousley (R.B.E. 27), 1938) where
it was first noticed by Mr. Iolo A. Williams about 1933. I do not
know if it persists.
6. R. cristatus DC. Cat. Hort. Monsp., 39, 1813 non Fries non
Wallr. Alien—a native of Southern Italy, the Balkans, Cyprus,
and Asia Minor. This is the species I recorded from Glamorgan
as R. graecus Boiss. and Heldr. (B.E.C. 1938 Rep., 148, 1939) but
Dr. K. H. Rechinger has since shown (Candollea, 11, 237-8, 1948)
that a specimen in De Candolle's herbarium at Geneva which is
the type of R. cristatus is the same species and the older name must
take priority. The species is rather closely allied to R. Patientia but
may be known by having distinct teeth on the valves, which all
bear tubercles, and by the characteristic side-nerves of the leaves
which make almost a right-angle with the mid-vein.
R. cristatus was discovered by Mr. D. H. Kert, on a disused em-
bankment on Hadleigh Marsh, v.-c. 18, in June 1950, on a L.N.H.S,
excursion (Lousley (4906306), 1949), thoroughly established.
7. R. crispus L. Native on the coast, probably introduced else-
where. Curled Dock. One of the commonest species growing in a
wide range of habitats throughout the whole of Essex. It is a
serious pest of agricultural land where it owes its success to the
large number of seeds which are dispersed by wind, water, and the
movements of man and animals, to the rapidity with which it can
mature its seeds, and to the ability of small pieces of root cut off
by cultivation to grow into new plants. By the sea it often has more
fleshy leaves and tubercles on all three of the valves round each
fruit when it is the variety littoreus Hardy.
8. R. conglomeratus Murr. Native. Sharp Dock. Probably fre-
quent throughout Essex in damp fields, by ditches and brackish
dykes and by ponds. For differences between this species and the
next see B.E.C. 1938 Rep., 133, 1939. This dock varies consider-
ably according to the amount of shade and moisture available and
thin-leaved shade-forms, such as I have seen by the pond at