CLASSIFICATION OF VEGETATION. 359 



on the other. Between the dry sand strand and the wet salt marsh 

 there is almost Lnvaribly a neutral belt, and so in most other eases. 

 Nevertheless, the plant formations are well-marked features of the 

 landscape, that can be recognized by any traveler. Indeed, next to 

 the water courses, the plant formations are the most important ele- 

 ments in the landscape of the Hat Coastal Plain. 



In the following 1 discussion of the plant formations of the Dismal 

 Swamp region, their physiognomy and taxonomic composition, with 

 special regard to abundant and conspieuoiis species, are first described. 

 Then follows, under the head of each formation, or formation elass, 

 a sketch of the more prominent ecological characteristics, preceded 

 by a discussion of the life; conditions. What may be termed bio- 

 logical forms — hi contradistinction to systematic forms — and, in gen- 

 eral, the more obvious adaptations to environment, are briefly treated. 

 The ecology of the sand strand and of the palustrine forest is dis- 

 cussed at greatest length, because in these formations life condi- 

 tions are extreme, and adaptations thereto are numerous and easily 

 detected. Tins is likewise the case with the salt marsh and the aquatic 

 formations, but here most of the biological, like the taxonomic forms, 

 are of wide distribution on the surface of the globe, and have been 

 described in many other publications. Hence it has seemed advisa- 

 ble to treat these formations more briefly. The sand strand and the 

 salt-marsh formations of the North Carolina coast were described in 

 an earlier paper; 1 and as the species, especially of the salt marsh, 

 are largely those that occur on the Virginia coast, climatic and other 

 conditions of the environment being likewise nearly identical, the fol- 

 lowing descriptions of the formations in Virginia may be regarded as 

 in part supplemented in the paper cited: 



The following is a synopsis of the formations and associations which 

 are easily recognizable in the plant covering of the Dismal Swamp 

 region : 



Maritime formations. 



Salt-marsh formation. 



Spartina stricta association. 

 Juncus roemerianus association. 

 Typha association. 

 Spartina patens association. 

 Baccharis-Hibiscus association. 

 Sand-strand formations. 



Beach and outermost dunes— Ammophila-Uniola association. 

 Middle (open) dunes. 



Dry soil — Myrica association. 



Wet soil, dune marshes — Juncus dichotomus association. 

 Inner (wooded) dunes. 



The high dunes — C^uercus virginiana association. 



The strand pine woods. 



1 T. H. Kearney, Contributions from the National Herbarium, vol. 5, No. 5. 

 23592— No. 6— 01 i 



