of Mississippi and Louisiana 73 



Chamae crista littoralis, Gerardia purpurea, Croton maritimum and a 

 goodly number of low mesophytes complete the association. 



The third type of sand plain is the forest-covered area to be 

 found only on the larger islands of the Mississippi Sound, where a 

 large area has been for a long period of time removed from the 

 immediate influence of the sea. Regarding Cat Island as a type, 

 the plain may be described as established, inasmuch as the surface 

 is subject to erosive agencies only to a very slight degree. There 

 are no water courses, unless one would attach that name to sloughs 

 in which the water is practically at a standstill. The wind can 

 nave but little effect upon the topography, as the soil is moist and 

 moreover is protected by the tree covering, while the force of the 

 wind is broken by the large dunes lying to the windward. The 

 surface is level save for a few low sand mounds which are not im- 

 probably to be regarded as fossil dunes, whose topography is at 

 present beyond the influence of erosive or moving agents. Else- 

 where the surface is lowered a little and the soil becomes much 

 wetter. Broadly speaking the whole area is covered by a forest 

 of pines of two species, Pinits australis and P. Taeda, with Sabal 

 glabra and Seren&a serrulata as prominent elements in the 

 undergrowth. In the wetter places under the shade of the palmetto 

 last named, a hepatic (Peliia sp.) was found in abundance in 

 August, and there is reason to believe that in the winter season a 

 number of species would be met with. In general, one may say 

 that the pine-covered plain is ecologically a part of the coastal plain 

 of the mainland, and that the flora differs from that of the pine 

 rrens of the coastal plain in scarcely anything except in the 

 number of species. So, too, with the mounds or fossil dunes above 

 referred to upon which one finds invariably a growth of live oaks, 

 generally Quercus geminata, or less frequently Q. Virgimana, 

 under the shade of which, and in a soil of much greater organic 

 content, grow a group of plants commonly found on the mainland 

 'n like situations. The tree trunks are clothed with incrusting 

 lichens, while from the branches grow Ramalina and some folia- 

 c eous species. On the lower parts of the trunks, and on the 

 ground, mosses {Leucobryum especially) and liverworts grow. 

 The lichen Cladonia rangiferina in rich fruiting condition was also 

 'ound growing in clumps on the ground. Beyond the shade of 



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