86 
EXnrBITION MEETING, 1050 
4. MS. AND DIAGRAMS. 
GEOGKAPHICAL ELEMENTS IN PLANT DISTRIBUTION OF GLOUCESTERSHIRE. 
The floristic, as distinct from tlie ecological, distribution of 
plants involves geographical factors, and is, in effect, to be 
determined by the comparison of floras. The total of species 
of any one country comprises an artificial flora ; true floras are 
independent of national boundaries. 
Professor J. R. Matthews {Joum. Ecol., 1937, 25, 1-90) has 
made a classification of true floras of continental Europe and 
has termed these Elements, distinguishing fifteen. Ignoring 
species which are common to many or all of them, he has listed 
the species which appear to belong to each Element in tl.e 
sense of having their head-quarters in it. 
As Britain has been almost completely recolonised from the 
continent since the last Ice Age, the geographical distribution 
of British plants must be studied by determining the locations 
of the species peculiar to each Element which have reached this 
country. 
The Tables exhibited are an attempt to indicate by figures 
and graphs the distributions of ten of the Elements which are 
those which appear to occur in Gloucestershire. The area ap- 
peared to be too small for one to hope for any conclusion?, but 
some points of interest .seem to emerge. 
TABLES . 
Each Table shows the distribution of the species of an Ele- 
ment in Gloucestershire and Britain in vertical columns. The 
first eight columns represent botanical districts as used in the 
Flora of Gloucestershire . These are (1 omitted) ; 2a, 2b The 
Vale; 3 R. Leadon area; 4 Forest of Dean and Wye Valley; 5 
Bristol district; 6 Stroud district; 7a North Cotswolds and 7b 
South Cotswolds. The next columns indicate areas in Britain 
- — South England, Midlands, North England, Lowlands and 
Highlands. a = acidophile, b = basic (calciphile), (N), (W), (S) = 
north, west and south marginal. Number at bottom of list of 
names = number of species whose distribution is general. Aliens 
omitted. 251 species, out of the Glos. total of 1189 species, = 
21 % , are included in the Tables. 
CONCLUSIONS. 
— Tables XI and XII show districts 4 and 5 as having a 
marked excess of species over the others. These two dis- 
tricts are the western ones and might be termed ‘Oceanic 
Districts’ . 
— This excess is much greater with Oceanic Elements than 
with Continental Elements. 
— The less variable graphs are of the three Continental Ele- 
ments, which ai’e more adapted to cold hills and dry Vale. 
