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. 
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