14 the vegetation of shackleford bank 



2. Creek marsh formation. 



The conditions of soil and soil water are the same as in the preceding 

 formation. The creek-marsh formation is not, however, covered at mean 

 high tide. 



The characteristic plants of this formation are Juncus Roemerianus, 

 Seutera palustris, and Eleocliaris albida. Abundant are Scirpus amer- 

 icanus, Gerardia maritima, Fimhristylis castanea. (See Plate VI A 

 and B.) 



3. Dune marsh formation. 



The soil is dark as in the salt marsh formation, but is not reached 

 even by winter high tides and the surface water is therefore fresh. 



a. Where the drainage is good, the surface water running into -small 

 creeks which make their way to the sound, occurs a rich plant covering 

 characteristic of which are Cladium jamaicense, Kosteletzl;ya virginica; 

 abundant are Boehmeria cylindric'a, Cyperus strigosus, Ipomoea sa- 

 gittata, Lippia nodiflora, Bacopa Monniera, {Moyinlera Monniera), 

 Ammania Koehnii, Dichromena colorata. 



h. Where the marsh is inclosed on all sides by neighboring high 

 ground, the drainage is very poor. As already mentioned, the black 

 soil is very impenetrable, and the surface water stands almost indefi- 

 nitely, becoming dark brown in color. Here Ludvigia palustris, PJuchca 

 foetida, P. camphorata, and Cyperus ha-span are the characteristic 

 species. 



c. In a few places such a poorly drained area seems liable to be cov- 

 ered by the highest winter tides. Here Proserpinaca pedinata and 

 Aspidium Thelypteris dominate the vegetation. 



d. In the lee of the highest dunes near the eastern end of the Bank 

 are permanent pools (1-3 feet deep) where Acorns Calamus and Salix 

 sp. are common. Around these pools occur many of the species noted 

 above. (See Plate YII A and B.) 



4. Tidal flat formation. 



This occurs wherever an area originally occupied by the dune marsh 

 has become sanded over. The soil is a mixture of the mud of the swamp 

 and the sand which has drifted in. The characteristic association is 

 made up of dwarfed Scirpus americanus, 6-8 inches high, and of Paspa- 

 lum distichum. Fimhristylis castanea and Spartina patens are often met 

 with. All of these are plants at home in the marshes. Besides them. 

 Euphorbia polygonifoUa and Cenchrus trihuloides occur as invaders 

 from the sand strand. 



