468 HARSHBERGER— INFLUENCE OF SEA WATER [April 22, 



water becomes gradually fresher and the salt marsh vegetation is 

 replaced gradually by fresh water marsh plants. 



T,2. Water from Pleasure Bay at the head of navigation. Sp. 

 gr. 1. 010. 



33. Water from ditch two feet deep in middle of Spartina patens 

 association. Sp. gr. i.oio. 



35. Water at head of small ditch with Scirpus pungens, Cicitta 

 maculata, Scirpus robustus. Sp. gr. 1.005. 



^y. Slue with Baccharis haliuiifolia and Spartina stricta niari- 

 tima. Sp. gr. i.oio. 



42. Hole in salt meadow on tension line between Jiincus Gerardi 

 (cut for hay) and an association of Scirpus pungens, Pluchea cam- 

 phorata, AtripJe.v hastata and Spartina patens on the other side. Sp. 

 gr. 1.005. 



44. Water from bases of plants of Typha angustifolia and Scir- 

 pus pungens. Sp. gr. 1.015.*' 



45. Water at third bridge above Pleasure Bay in the middle of 

 an association of Spartina stricta maritima, Scirpus pungens, S. ro- 

 bustus. Sp. gr. 1.005. 



46. Above the fourth bridge in middle of a Spartina stricta mari- 

 tima association. Sp. gr. 1.0005. 



47. Here a pure association of Scirpus robustus. Sp. gr. 1.0005. 



48. Association of Zizania aquatica and Scirpus robustus. Sp. 

 gr. 1.0005. 



50. Water from inner edge of an association of Typha angusti- 

 folia (tall), Peltandra virginica and Cicuta maculata. Sp. gr. i.ooo. 



51. Muddy cold water from a hole in an association of Sagittaria 

 latifolia {=S. I'ariabilis) , Cicuta maculata, Typha angustifolia, 

 Polygonum sagittatum. Sp. gr. 1.0015. 



52. Water from channel under last bridge. Sp. gr. 1.0015. 

 The fact that such salt marsh species as Spartina stricta maritima 



mingles with fresh-water marsh species under almost fresh-water 

 conditions is to be explained by the occasional inundation of such 

 plants by more strongly saline water at exceptionally high tides, so 

 that the exceptionally high tides enable the salt grass to persist sur- 

 rounded by fresh-water marsh species. The salt marsh species can 



" Prolnibly due to evaporation. 



