300
THE ESSEX NATURALIST
Botanical Report for 1964
By S. T. Jermyn, F.L.S.
As there was no report for 1963 the individual plant records
given in this one will cover the two years.
In 1960 I first started tabulating the records on a 10 km. grid
square basis in addition to keeping them by parishes. The method
of tabulating used is much more precise in showing how many
records there are by squares and in which of these the plants
occur. I must explain here that due to the size of Essex, with 57
10 km. squares, and the small number of recorders, it has not
been found possible to give more than one plant record for each
square.
This year a certain amount of revision has taken place and only
records made since 1930 have been included. This has meant that
several hundred records made prior to this date have been taken
out. This "date line" was not arbitrarily fixed but was taken as it
coincided with the Atlas of the British Flora, the Essex records
from which had already been included.
This loss has been more than made up by the normal additions
for 1964 and the new Essex records taken from the Hand-List of
the Plants of the London Area, also the Bishops Stortford N.H.S.
list of Vascular Plants for their area for which Mr J. Fielding
gave valuable help in extracting the Essex records. The total
records for 1964 (allowing one plant for each square) stands at
30,839, an increase on 1963 of 2,956. The average for each square
is now 535 which shows a considerable increase on the 1960 figures
when the average was only 322.
The individual plant species have risen from 1237 in 1960 to
1777 in 1964; an explanation of this will be given later.
The comparison and analysis of the records by squares is very
interesting but in a short article such as this, it will not be possible
to give all these figures, so, instead, I will show how many species
occur in a given number of squares throughout the county: —
834 species 47.0% occur in from 1 to 5 squares only
360 „ 20.3% „ „ „ 6 „ 20
246 „ 13.8% „ „ „ 21 „ 40
337 „ 18.9% „ „ „ 41 „ 57
1777 „ 100.0% 57
The number of species found in one square only is 430 and
there are 149 species found in every square.
The high proportion found in 5 or fewer squares is due to
several factors. First, all the "rubbish tip" weeds are included
and there have been some really large dumps on Thames-side at
Barking, Dagenham, Grays, Pitsea, Wennington, Purfleet and
Canvey since the 1930s. Many others can be found all over the
county and from these a large number of records have been made.