ECOLOGICAL RELATIONS OF THE FLORA. 



47 



in maximuni and minimum as shown l>y comparison Ijv days shows 

 that the drop in temperature averaged about twice as much for the 

 beach as for the woods. In July the minimum at no time Ijecame 

 low enough to affect the plant activity, luit in growing months when 

 the temperature approached freezing this excessive difference would 

 become an imi)ortant factor, for it must be considered that during the 

 ifight the wind still vigorously exerts its drying action. These records 

 were for air temperatures, but soil temperatures on the beach and in 

 the woods would show the same or greater range in temperature due 

 to the low specific heat of sand (Warming, 1909, p. 52, gives the specific 

 heat of sand as .2). 



Detail of the Calamovilfa-Ammophila Association. 

 Dominant Species: 



CalavTovilfa longi folia. 



Ammoph ila arenaria . 

 Sub-Dominant Species : 



Equisetum hyemale intermedium. 



Elynius canadensis. 



Populus tremuloides. 



Rumex crispus. 



Arahis lyrata. 



Potentilla anserina. 



Prunus pumila. 



Lathyrus maratimus. 



Oenothera biennis. 



Convolvulus sepium. 



Solanum nigrum. 



Erigeron canadensis. 



Artemisia caudata. 



Lactuca canadensis. 



Cirsium arvense. 



Cirsium pitcheri. 



