Woods of North-East Kent . 873 
Similarly several plants occur only on the deepest soil near the northern 
boundary of the wood :— 
Gnaphalium uliginosum , L. 
Rumex obtusifolius , L. 
Rumex sanguineus , L. 
Polygonum aviculare , L. 
Polygonum Persicaria , L. 
Juncus bufonius, L. 
Bromus erectus , Huds. 
Bromus ramosus, Huds. 
Poa nemoralis ) L. 
Riviniana and F/0/0 Reichenbachiana are both found, the former 
occurring in abundance on the greater part of the Clay, while the latter is 
almost confined to the deeper soils. Over a considerable part of the area 
the soil is approximately 4 feet in depth, and several plants are found here 
which are usually absent from the shallower and deeper soil:— 
Hypericum perforatum, L. Holcus lanatus, L. 
Digitalis purpurea, L. Holcus mollis , L. 
A nthoxanthum odoratum , L. Pteris aquilina, L. 
Digitalis purpurea is scattered, while Pteris aquilina is found in a few 
small clumps. Several Grasses, on the other hand, are abundant, especially 
Anthoxanthum odoratum and Holcus mollis. This latter is a widely 
distributed woodland species and its occurrence here is not unexpected, but 
this is not the case with Anthoxanthum. These species each possess a 
shallow root system and would presumably come into direct competition 
with each other ; the time of flowering is, however, different, and the growth 
of Anthoxanthum is to a large extent completed before the flowering period 
of Holcus mollis commences. As a result of the Rothamstead manurial 
experiments, Lawes, Gilbert, and Masters ( 10 ) found that Anthoxanthum 
odoratum became prominent in unmanured plots where there was small 
growth of herbage and little activity of struggle. In experiments carried out 
at Chiswick, where Anthoxanthum was grown separately, the highest degree 
of vigour was obtained when both mineral and nitrogenous manures were 
supplied. The rapid decomposition of the humus accumulated during the 
shade period would probably produce somewhat similar conditions to those 
of the latter experiment, and at the same time the competition here would 
be considerably less than in a meadow. These considerations, together with 
the wide distribution of A nthoxanthum, perhaps partly explain its abundance 
in this situation. Holcus lanatus, another shallow-rooting species, also occurs 
in considerable abundance. This plant, in the Rothamstead grass plots, 
grows best under manurial conditions which do not tend to general luxuri¬ 
ance ; it attains its greatest percentage with liberal nitrogenous and mineral 
manure. 
Hypericum perforatum occurs in considerable quantity over the whole 
Clay area, but is especially abundant on soil varying from 3 to 5 feet in depth. 
On the shallow soils it is partly replaced by Hypericum hirsuium , while on 
