MARITIME ASSOCIATIONS 279 



and constituting an edaphic modification of the ordinary 

 reed-swamp. The dominant plants are Juncus Gerardi, 

 Scirpus maritimus, Glyceria maritima, and in some parts 

 Phragmites communis also. Where the soil is drier the 

 plants are not so tall-growing as in the reed-swamp ; this 

 type may be called a salt-meadow. 



Characteristic salt-marsh plants are : Aster Tripolium 

 (sea-aster), Statice Limonium (sea-lavender), Armeria mari- 

 tima (thrift), Plantago maritima (sea-plantain), Salicarnia 

 heriacea, Spergularia salina (sea-spurrey), Sueda maritime 

 (sea-blite), Atriplex portulacoides (sea-purslane), Artemisia 

 maritima (sea-wormwood), Beta maritima (sea-beet), 

 Triglochin maritimum (seaside arrow-grass), Gochlearia 

 officinalis, C. anglica, and C. dardca (scurvy-grasses), 

 Glaux maritima (sea-mUkwort), Atriplex littoralis (grass- 

 leaved orach), Scirpus triqueter, 8. rujus, Hordeum mari- 

 timum (sea-barley). 



2. Flora of Sandy Shores. — On sandy shores the con- 

 ditions are quite different from the salt-marsh. Except 

 within reach of the tides, the amount of salt present in the 

 soil-water is comparatively small. The porous soil allows 

 rain to drain away very rapidly, and the plants are sub- 

 jected to long periods of drought. The xerophjiiic 

 character of the plant, therefore, is not due to physiological 

 dryness, but to physical. Yet the adaptations are the 

 same in both cases — succulent plants are as common here 

 as in the marsh ; indeed, some are found in both situations 

 — -e.g., thrift, scurvy -grass, sea-plantain, and beet. 



Where strong winds prevail in a direction at right angles 

 to the coast the sand is blown inland, and accumulates in 

 long sand-hills or dunes running parallel to the shore. 

 Unless the dune is completely covered with vegetation — 

 and this is rarely so — the sand is carried still farther inland, 

 and a second or even third line of dunes aris^ on the 

 landward side. The flora of the dune varies according to 

 the compactness of the sand, and to some extent according 

 to its chemical composition. Most of the sand consists of 

 quartz-particles, and the soil is consequently very sterUe, 

 but when the remains of marine shells are present the 

 soil is richer, and many calciphilous plants occur. 



On the sand immediately above the mean high-water 

 mark, and only covered at very high tides, a narrow zone 

 of strand-vegetation occurs. The water within reach of 



