436 BOTANICAL SURVEY OF DISMAL SWAMP REGION. 



2. The scarcity of terrestrial herbaceous vegetation. 

 ;}. The abundance of large, high-climbing lianas which open their 

 blossoms in the tree tops. 



-1. The almost omnipresence of a woody, bamboo-like grass. 



5. The occurrence of vascular epiphytes. 



6. The presence of a woody, loranthaceous parasite on the trees. 



7. The abundance of thick, evergreen, laurel-shaped leaves, with 

 shining upper surface. 



Of course the tropical influence is, after all, weak, and one can 

 readily call to mind many characteristics of the Rain Woods that are 

 not represented in this far extra-tropical region. Such are epiphylly 

 (epiphytes on leaves); showy-flowered epiphytes and parasites; cauli- 

 flory (flowers produced from the old wood of trees) ; trees with com- 

 pound leaves; trees with "plank roots;" certain ombrophobous 

 modifications, such as long-channeled points to the leaves, which 

 carry off rain water, etc. Moreover there are many ecological forms 

 that coincide with large systematic groups of the Tropics, and are 

 wanting in the Dismal Swamp region, e. g., tree ferns, palms, climb- 

 ing and epiphytic aroids, epiphytic orchids, epiphytic trees and 

 shrubs (Ficus, Clusiaceae). 



FKESH-WATEK MARSH FORMATIONS. 

 liEED MARSH FORMATION. 



Along rivers — Typha-Sagittaria Association. — Above the normal 

 influence of brackish water the larger streams of the region are 

 fringed by a usually narrow belt of marsh vegetation, which, on the 

 one hand, passes gradually into the salt marsh downstream; on the 

 other, into the wooded swamps above. Typical examples are to be 

 seen along the Nansemond, the Northwest, the Pasquotank, and 

 other rivers, usually at or just above the upper limit of navigation. 

 Like the marshes with a saline substratum, this formation is charac- 

 terized by the preponderance of species with a grass-like habit and 

 by the scarcity or entire absence of woody plants. When these 

 occur, they are usually small cypress trees (Taxodium distich urn), 

 bushes of alder (Alnus nujosa), willow (Sal Lie nigra, 8. ivardi), red 

 maple (Acer rtibrmu), Ilea virginica, Magnolia virginiana, Rosa Caro- 

 lina, Clethra alnifolia, Cephalanthus occidentalism etc., which some- 

 times support certain lianas — Hntilax laurifolia, Berchemia scandens, 

 Clematis crispa. Woody plants are usually absent from the wettest 

 part of the marsh which borders the open channel of the stream, and 

 first appear on higher ground farther back, becoming more and more 

 numerous until the open marsh passes over into the swampy forest. 



The outermost growth in water commonly 15 to 30 centimeters (6 to 

 1l> inches) deep is most often dominated by the cat-tail (TyphalaM- 

 folia), which sometimes forms a nearly pure 1 association. A tall 

 Sagitlaria (S. lane if alia) and the showy pickerel weed (Pontederia 



