Fenis of the Dismal tiwanip, Virginia. 63 



.has also undergone some change on account of its unusual 

 environment. 



The flooded condition of the true peaty swamp floor for several 

 months of the year prevents the growth of ground ferns, except 

 the water-loving woodwardias ; therefore all the species of the 

 swamp proper which grow nearthe ground occur just above the 

 high-water line and rarely more than three feet above it. 



A systematic examination of the whole swamp for ferns has not 

 been possible, but enough has been learned to show that a number 

 of species have adapted themselves to very unusual conditions, 

 and that some have undergone changes from the normal type. 

 The main factor in determining the character of the pteridophytic 

 life is the flooded condition of the swamp floor for several months 

 annually, but this is less potent now than formerly. 



LIST OF SPECIES. 



1. Botrychium obliquum Muhl. Oblique Grape Fern. 



On June 10, 1899, 1 found four plants, growing with other species on logs, 

 at the side of Washington ditch. They were sterile fronds of the previous 

 year's growth. The fronds are less ample and the divisions shorter, more 

 rounded and more widely placed than in any specimens from about Wash 

 ington. The dried roots are stronger, blacker, and more abundant. 



2. Struthopteris * regalis (Linn.) Bernh. Royal Fern. 

 Osmunda regalis Linn., Sp. PI. p. 1065, 1753- 



Abundant, usually in large clumps scattered throughout the swamp 

 and always on dead stumps except in the sandy areas. 



In many cases hundreds of dead persistent stipes testify to the great 

 age of the clumps. Just above high -water mark mosses have established 

 a foothold in a broad ring around the old knees of the cypresses, the 

 bends of gum roots, and logs. Various plants, especially ferns, take root 

 in this moss and often reach a large size. The oddity and beauty of such 

 growths are striking, especially on a well-preserved knee where the red 

 dish apex rises several inches above the surrounding moss. (See plate I, 

 Fig. 7.} 



* The ferns usually placed in Osmunda evidently belong to Bernhardi's 

 genus Struthopteris (not Struthiopteris of authors). The essential features 

 of Bernhardi's description are as follows: 21. Struthopteris mini. Spo 

 rangia subglobosa, bivalvia. E. g. Osmunda regalis. L. Cinnamomea. 



L. Clayloniana. L. * * *. Obs. 2. Caue ne Struthopteridem 

 meam cum Struthiopteride Hall, confundas. (Journ. fur die Botanik, 

 Band 2, 126, 1801.) 



