THE COAST-FLORA OF THE CLACTON DISTRICT. 
203 
On the other hand the physical constitution of mud, and its 
high nutritive value, are antagonistic to the action of salt. 
This may explain why the plants are frequently luxuriant in 
size, though xerophytic in structure. 
The rain-fall at Clacton is usually below 20 inches a year, 
and is more or less distributed over the whole twelve months. 
Extreme drought for long periods does therefore not occur, as it 
does, for instance, in the steppe, where vegetative growth is 
entirely confined to the rainy season. There are, however, species 
growing on the coast whose term of annual growth lies in winter 
or early spring, and who pass the hot season in the form of 
seed or spore. Such is the case of some spermophytic annuals 
(Cerastium, and, to a certain extent, CochUaria officinalis and 
Lepidium ruder ale), but more particularly of the mosses which 
cover all the sandy shore in winter and early spring. Another 
effect of rain will be the washing away of salt in those higher 
parts of the littoral meadow that are only covered by an excep¬ 
tionally high and stormy tide. There are places where the 
vegetation can scarcely be said to be Halophilous—so numerous 
are the invaders from the ordinarv meadow, dune or waste land. 
A factor of smaller importance (for our purpose) is light ; 
like wind it tends to accelerate transpiration. There being no 
trees, there is little protection against light, and several plants 
show definite modifications against insolation, such as the as¬ 
sumption of profil-lie in the leaves of Atriplex portalaco'ides. 
Wind-sheltered places are conspicuous for the larger size of the 
plants ; much of the dwarfing appears to be due to exposure to 
wind. 
It is not always easy to determine whether a plant is a genuine 
Halophyte, whose life depends on the presence of salt, or a non- 
Halophilous inland plant which is able to endure the salt without 
danger to its existence. I propose, therefore, to follow the 
clearer division into Psammophytes and Pelophvtes, irrespective 
of their relation to salt. 
I. PSAMMOPHYTES. 
I have already sketched the reasons why the vegetation 
of the sandy shore must be extremely xerophytic. It has been 
said, also, that psammophytes fall into two groups, the Halo¬ 
philous and non-Halophilous. 
