266 THE ESSEX NATURALIST
British ones from their cotyledons—but it needs a great deal of
practice to do so.
The popular distinction between Docks and Sorrels is one
accepted by botanists. The former have male and female organs in
the same flowers, while in the latter they are generally produced on
different plants, and there are other differences. But for botanical
purposes the distinction does not go far enough, for whereas in
the Sheep's Sorrel the tepals are scarcely larger in fruit than in
flower, in the Common Sorrel they increase greatly in size as they
do in the Docks. Modern systematists therefore divide the genus
Rumex into three subgenera (making two of the Sorrels) as
follows:
Subgenus I. ACETOSELLA (Meisn.) Rech. fil. Male and female
flowers on different plants. Inner tepals of the female flowers not
enlarged, or only a little enlarged at the time of fruiting, all without
tubercles. Leaves usually hastate or sagittate.—The Sheep's Sorrels.
Subgenus II. ACETOSA (Campd.) Rech. fil. Male and female flowers
on different plants (or on the same plants in certain species which
do not occur in Essex). Inner tepals of the female flowers much
enlarged after fruiting, without tubercles or with a minute tubercle
at the base. Leaves usually hastate or sagittate.—Common Sorrel.
Subgenus III. LAPATHUM (Campd.) Rech. fil. Male and female
organs in the same flowers (the male usually maturing first). Valves
much larger than the nuts. Base of the lower leaves wedge-shaped,
rounded, or cordate—never hastate or sagittate.—Docks.
In the following notes I have collected together the records of
Docks and Sorrels from Essex known to me and likely to be useful
as a basis for the new Flora. For botanical purposes the county is
divided into two, and the resulting "vice-counties" are referred to
as North Essex or v.-c. 19, and South Essex or v.-c. 18. The
sequence of species is based on recent foreign work and is likely to
be the one adopted in forthcoming accounts of the British species.
SUBGENUS I. ACETOSELLA.
1. R. Acetosella L. emend. Love. Native. The Common Sheep's
Sorrel is plentiful throughout Essex (v.-cc. 18 and 19), and
especially on sandy and acid soils where it spreads rapidly by means
of branches of the roots running an inch or two below the surface
of the soil. An allied species, R. tenuifolius (Wallr.) Love., occurs in
plenty on sandy soils in Suffolk and Norfolk and locally in Surrey
and should be searched for in Essex. (A specimen from railway
line, Colchester North Station, 1875, J. C. Shenstone in Hb.
Essex F.C. may be this). A third species, R. angiocarpus Murb.,
has been recorded from Britain. All three have different chromo-
some numbers and they may be known by the characters set out
in the following key (after Rechinger, Candoliea, 12, 15-16, 1949):
1. Valves fused to the nut (fruit)............ R. angiocarpus
1. Valves not fused to the nut.