PELOPHILOUS FORMATION OF LEFT BANK OF SEVERN ESTUARY. 15 
I am driven to the conclusion that their appearance would be far 
worse had they possessed a hairy cuticle. Also it seems to me 
that the plants collect more mud as they grow older, presumably 
because the cuticle of the older plants is rougher and more cracked 
than that of the young plants. It seems to me then that the 
glabrous cuticle may be of use to the plants in preventing them 
from being covered with a layer of mud sufficiently thick to clog 
stomatal apertures and to obstruct the free entrance of air and 
light so necessary to their healthy growth. 
Another great characteristic of the plants of this formation, is 
the tenacity with which they maintain their position in the mud, 
not merely securing to themselves a foothold, but often by their 
low much-branched stems embedded in the mud, or by the tenacious 
tangle of a fibrous root, actually holding around them a part of 
the zone which otherwise would succumb to the tide. Owing to 
the layered arrangement of the zones, the falling tide exerts a 
very considerable scour upon them, and they would disappear far 
more rapidly were it not for the holding power of the plants. 
The force at work causing denudation was well brought home to 
me one early spring morning upon which I had gone to Portishead 
to watch the effect of these tides on vegetation. The morning was 
very still, hardly broken by any noise at all as the tide came to 
its full height, but it had not been falling long, before, from all 
directions, there came a rapidly increasing sound of falling water. 
Heavy temporary waterfalls, falling perhaps from one to two 
feet, and extending for miles along the shore, soon brought to 
one's notice the scouring effect produced by the falling mass of 
water, and the masses of earth cut away and fallen from the top 
zone, and the rather deeper scour on the innermost edge of each 
zone where the falling water impinged upon it, needed no further 
explanation. It is quite evident that the only thing that enables 
these stepped zones to withstand the tidal scour so well is the 
close mat of plants upon their surface. 
The plants at the edge of a zone are fixed most firmly ; it is 
no uncommon thing to see a small Festuca or Aster or other 
plant at the edge of a zone, not more than three or four inches 
above the level of the mud, but with roots striking down into 
the soil from two to three feet or even further. Aster Tripolium, L., 
Statice Armeria, L., and Festuca rubra, L., are examples of plants 
which help to retain the mud surface from denudation by their 
closely matted branched stems just below and upon the surface 
of the ground. 
A consideration of this phenomenon leads one to wonder whether 
the various fences, stone barriers, &c., employed are the most 
effective means of preventing tidal scour ; or whether more might 
not be done by means of a sloping bank covered by the natural turf, 
and at the same time by its contour free from these little water- 
falls during the ebbing tide, and therefore far less liable to scour. 
