Seasides and Strand Plants 



along the shore are practically not colonisable until 

 they accumulate and become stationary. Then they 

 are rapidly overgrown by a miscellaneous series of 

 plants of which most are common weeds. But on such 

 shingles one may find the yellow flowers and long pods 

 of horned poppy (Glaucium luteum), or the particularly 

 spiny rose (Rosa spinosissima), and many of the charac- 

 teristic sand plants. These last are scattered along the 

 shore just above high-water mark, and would seem to 

 be growing in pure sand, but generally they are rooted 

 in buried seaweed or drift rubbish only covered over by 

 the sand. 



These sand plants are all adapted to very dry 

 conditions, as one would expect, and include Glaux, 

 Honckenya, Isle-of-Man cabbage, various Atriplex sp., 

 Samolus Valerandi, &c., and many rare plants are to be 

 looked for in the more sheltered places. But the theory 

 of the plant world in dealing with sand can only be 

 gathered from a series of dunes. On a very windy day, 

 any one watching a sand-dune can scarcely believe that 

 any plant could possibly deal with it. Not only is the 

 soil thoroughly bad, for it is full of salt, very loose, porous, 

 and exceedingly dry, but at mid-day the sunny side of a 

 dune may show a temperature of 80 C., whilst at night 

 the radiation of heat will be exceedingly rapid and cool 

 the surface far below that of normal soils. The worst 

 point, however, is that it is not fixed but always shifting. 

 In storms, sprays and showers of small sand particles 

 are torn off by the wind. Much of the dust consists 

 of angular flinty particles which, when blown by a gale, 

 can polish and wear down the very hardest rocks. The 

 dune itself moves, for the larger particles are drifted up 

 the long seaward slope and tumbled over the crest. 



Yet, except in a few rare and exceptional instances, 

 plants do annex and colonise sand-dunes. 



164 



