Spruce and tamarack swamps. 
(Cane swamp societies. 
Salt marsh societies. 
Salt shores where gradient is low and soil nitrophytic. 
Water brackish. 
Plants xerophytic. 
Structural adaptations in salt marsh plants. 
a. Abundance of air spaces. This is ‘corselated 
with ability of piant to bear long inundation 
at high tide. 
b. Ability of root hairs to resist plasmolysis in 
highly concentrated sea water (ex., 90 per 
cent). 
5. Individuals of same species more stunted close to 
water's edge when submerged for longer time. 
Examples, the maritime ruppia (Ruppia maritima), 
glasswort (Salicornia) Sedge spartina (Spar- 
tina stricta glabra). 
Shores of marl ponds. Soil calcareous. 
Vegetation often xerophytic. 
Ga NAS 
Ex., shrubby cinquefoil (Potentilla fruticosa—Dasi- 
phora fruticosa). 
XX. AQUATIC PLANT SOCIETIES. 
I. General Considerations. 
How differ from sand swamp or mud swamp societies and 
gradation one to the other and to soil societies. 
Relation of plants to water. 
I. Some entirely submerged. 
2. Some float on surface of water. 
3. Some stems submerged, leaves on surface. 
4. Some leaves erected above water, near semiaquatics. 
Characters of aquatic plants. 
I. Supported by the water. : 
2. Only a sight development of mechanical tissue. 
3. Provided with air by large air spaces throughout the 
tissue. | 
4. Little development of root hairs. 
5. Where roots are developed they are used chiefly as 
holdfasts. 
