270 THE ESSEX NATURALIST
occurred occasionally at docks and on rubbish dumps. From
Essex I have seen material from Dagenham (Melville (278), 1927,
Hb. Druce) and Rainham (1927, Hb. Kew)—both v.-c. 18.
14. R. maritimus L. Native. Golden Dock. As the scientific name
suggests, this plant is most usually found round pools and brack-
ish dykes near the sea. But it is by no means restricted to the coast
in Britain generally and there are a few inland Essex localities.
In v.-c. 18 it was found near Purfleet by Benson and Ibbotsdon
before 1862 (Gibson, Fl. Essex, p. 265) and again by H. and J.
Groves in 1875 (Hb. Hanbury). Ibbotsdon also got it at Wenning-
ton where I was able to study its life-history in 1938 and 1939
(B.E.C. 1938 Rep., 143-4, 1939). Here it grew as a luxuriant over-
wintering plant round a pond. At Hare Street, Romford, where
Cooke gathered it in 1912 (Hb. L.N.H.S.), it was still farther from
the sea. I have also seen it in marsh ditches between Tilbury Fort
and East Tilbury in 1944 and on Bowers Marsh, near Pitsea,
where S. T. Jermyn found it in 1948. There is also a specimen from
Rainham, 1848, Ex-Herb. Benson, in Hb. Essex F.C.
In v.-c. 19, R. maritimus was found near Dovercourt by Babing-
ton in 1877 (Hb. Cantab.) and by Sherrin in 1905 (Hb. S.L.B.I.).
I saw it by dykes at Lee Sands, St. Osyth, in 1948 (Hb. Lousleyi
and Britton found it in a reed swamp at Clacton-on-Sea in 1912
(Hb. Kew).
15. R. palustris Sm. Native. Yellow Marsh Dock. This is re-
corded from South Essex, v.-c. 18, for which there are records in
Gibson's Flora, from Plaistow, Wanstead Park, Hale End,
Upton, and also Dagenham and Purfleet. From "on the Forest
near Hale End" I have seen specimens collected by Edward
Forster (1765-1849—see Essex Nat. 19, 221-37, 244), in the
herbarium at the Natural History Museum and from Gaysham
Hall, Barkingside, 1926, T. W. Willis (Hb. Essex F.C.); from a
marsh ditch at Dagenham I gathered it myself in 1934 and 1944.
There is no reason to doubt any of the old records but this species
has been so often confused with R. maritimus that care should be
taken in determinations. The differences between the two plants
are set out in an earlier paper (Lousley, B.E.C. 1941-2 Rep., 571,
1944). From v.-c. 19 there is a specimen (in Hb. Essex F.C.)
collected in 1912 by C. E. Britton (977) from a reed-swamp west
of Clacton-on-Sea, where it grew with R. maritimus.
hybrids. In the subgenus Lapathum hybrids are extremely
common and often prove puzzling to beginners who are unable to
reconcile their specimens with the descriptions of species as given
in floras. Fortunately there is usually no difficulty in recognising
hybrid material as such. In this, fruits are seldom matured and it
is only in scattered flowers that the tepals enlarge after pollination.