152
PLANT DISTRIBUTION.
Unfortunately Miss Thresh and Dr. Thresh were obliged to leave somewhat
early in the evening, and an adequate discussion of the paper was impossible.
Mr. T. S. Dymond, F.I.C, made some remarks on the chemical parts of the
paper, and asked whether the waters had been tested for the rarer elements.
It was suggested that it might be well to appoint some evening when the very
interesting points raised in the paper could be fully discussed.
On the motion of the Chairman a very hearty vote of thanks was passed to Mr.
Christy and Miss Thresh for the paper, which will be published in the Essex
Naturalist.
ON PLANT DISTRIBUTION IN THE
NEIGHBOURHOOD OF FELSTEAD.
By JOHN FRENCH.
Read January 25th, 1908.
THE general aspect of vegetation in Essex is so well known
that a word is sufficient to conjure up a whole phalanx of
plants in mental array. Generally speaking, it may be described
as crowded. It is to this crowded state that the chief interest
attaching to plant distribution is due. The struggle for mastery
gives rise to all manner of cross currents, and these, reacting
upon each other, although they complicate the problem, invest
it at the same time with very much interest. We purpose,
however, taking a simple line in this paper by presenting tables
that bear only on one aspect of the subject.
The introduction of a new species of plant into a district that
is already crowded with vegetation is attended with great
difficulties. For the introduction alone, in the case of plants
propagated by seeds, four conditions are necessary, namely, (1)
that there be a good seed ; (2) that a proper locality occur;
(3) that the conditions of successful germination be present ; (4)
that these three conditions be present together at the same time
and at the same place. For the further establishment of the
plant in a crowded district a fifth condition arises, and that is
that the new comer shall have some advantage over those
plants already in possession. If it were not so, the new incoming
plant would either succumb or make no progress. The advan-
tage might be slight, and of so subtle a character as to elude
observation, but it is essential that it be there. These five con-
ditions may be applied to explain the spread or diminution of
plants generally. It is obvious on reflection that in a state of