VOL. XIII, PP. 61-70 SEPTEMBER 28, 1899 



PROCEEDINGS 



OK THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



FERNS OF THE DISMAL SWAMP, VIRGINIA. 

 BY WILLIAM PALMER. 



The ferns of the Dismal Swamp may be divided into three 

 distinct groups according to their place of growth: (1) arboreal 

 species, (2) true swamp species, and (3) ground species. The 

 first group may be divided into two subdivisions : (a) those 

 growing on fallen mossy trunks, about the bases of living 

 gum trees, on dead cypress knees, bent gum roots, and on 

 decaying stumps ; (6) those growing exclusively on trunks and 

 brandies of living trees. The first subdivision (a) comprises 

 the following species: Dryopteris marginal-is, D. spimdosa, D. 

 goldieana celsa, Polystichum acrostichoides, Aspleniam platyneuron, 

 Strutkopteris regalis, S. cinnamomea, Botrychium obliquum. The 

 second subdivision (6) contains but one species, Polypodium poly- 

 podioides, which grows exclusively on the trunks and larger 

 branches of living trees, usually high up in the tops, and prob 

 ably on all the species of deciduous trees. The true swamp 

 ferns include but two species, Woadwardia, virginica and W. areo- 

 lata, which grow on the peaty remains of former vegetable life, 

 always in wet places and often, especially the former, in water. 



The ground ferns occur, not in the true peaty swamp, but in 

 the surrounding low sandy area, which nevertheless constitutes 

 a very large portion of the Dismal Swamp. These are Dryopteris 

 n^veboraceasis^D. thelypteris, Asplenium filixfcernina, Pteris aquilina, 

 Onoclea semibilis, Struthopferis regalis, S. cinnamomea. But one 

 fern ally (Selaginella apus) has been found. 



A study of many forms of the life of this vast swamp reveals 

 the interesting fact of the occurrence in abundance of many 



16-Bior,. Soc. WASH., Voi,. XI IF, 1899 (61) 



