140 PLANT-LIFE ON LAND [CH. viii 



constant in direction, but not necessarily great in 

 power. The principle is the same as that which may 

 be followed on any Dune of small size, where the 

 wind has got the better of the binding vegetation. 



Enough has been said to show the instability of 

 the White or Shifting Dune. But provided that the 

 conditions be quiescent, various plant-growths appear 

 between the tufts of Marram or other prime formers 

 of the Dune. These gradually cover the surface, 

 converting the formation to what is called Grey or 

 Stationary Dune. This constitutes a third zone on 

 the landward side of the chain of White Dunes. 

 The plants that bring this about are usually of low 

 growth and straggling habit. Small annuals or 

 biennials are found among them, such as Whitlow 

 Grass, Teesdalia, and species of ]Mouse-ear : small 

 Leguminous plants, such as Lotus, and species of 

 Clover and Vetch. The Ladies Bedstraw, various 

 small grasses, such as Air a, Agrostls, and Sheep's 

 Fescue : or where in the hollows water will sometimes 

 stand, species of Rush and Cotton Grass and Sedge 

 may appear. Mosses may take their place in this 

 attractive little Flora, some Fungi such as Puff-Balls 

 and Clavarias, and Lichens such as Cladonia. But 

 amongst the most effective plants which give a greater 

 degree of consistence to the Grey Dunes are certain 

 woody plants, such as the Creeping Willow {Salix 

 rej^eus), with its almost prostrate twigs, while the 



