VEGETATION OF SANDY SEASHORES 7 



(i) Those belonging to shifting sands ; in different parts of the 

 country, different plants will be found, but the most common are 

 the Sea Rocket and the Saltwort ; this may therefore be called 

 a Salsola-Cakile Plant association. (2) The Marram association, 

 situated more landward and characterised by the formation of 

 sand-dunes, owing to the binding powers possessed by the rhizomes 

 of the plants. Here the part played by the wind may be noticed. 

 Coming in contact with sand, the wind drives it onwards, piling 

 it into irregular heaps and ridges called " dunes. " Their general 

 direction is transverse to the prevalent course of the wind. The 

 coast of Norfolk is fringed with sand-hills, fifty to sixty feet high. 

 Long tracts of blown sand are found on the Scottish and Irish 

 coast-lines. Sand-dunes extend for many miles along the French 

 coast, and Flanders and Holland ; off Holland they are occasionally 

 over two hundred feet, though their average is, as in Norfolk, 

 fifty to sixty. When not fixed by sand binders, the dunes may 

 travel inland. On the low shores of the Bay of Biscay their rate 

 is about sixteen feet per annum, and in their progress they have 

 at times overwhelmed whole districts. This destruction is now 

 prevented by the planting of pine forests. 



In making observations on the flora of a sand-dune, the plants 

 found in the hollow between the summits of the dune will be 

 greater in number and variety, for the position is more sheltered, 

 the force of the wind is less felt, and there is more shade. These 

 all help to form a thick sward, which renders the sand less liable 

 to be blown about. The next stage is the formation of a dune 

 pasture. Here there are many more plants present. The most 

 abundant are Centaury, Convolvulus, Thyme, Ragwort, Plantain, 

 and Chamomile. 



The following table is an attempt to compare the Plant For- 

 mations of muddy and sandy seashores ; the figures denote the 

 order of succession. 



PLANT FORMATIONS 



MUDDY SHORES SAXDY SHORES 



_ ( Sea Wheat -Grass 

 (i. Sahcornia I -\ Q , , 



PLANT P en " { 2 . 



Glyceria fluitans 2. Psamma 

 Juncus Gerardii 3. Sward-fo: 

 Substituted 4. Salt Marsh pasture 4. Dune pasture 



:s Intermediate 3. Juncus Gerardii 3. Sward-forming Plants 



