28 OUR NATIVE FERNS AND THEIR ALLIES. 



LITERATURE.* 



Bessey. Botany. (See p. 23.) 



GoEBEL. Outlines of Classification. (See p. 23.) 



De Bary (A.). Comparative Anatomy of Phanerogams 

 and Ferns. 8vo. Oxford, 1884. (Macmillan & Co.) 



Campbell (Douglas H.). A Third Coat in the Spores of the 

 Genus Onoclea. In Torrey Bulletin, xil, 8, 9 (Jan. 1885). 



Schrenk (Joseph). The Dehiscence of Fern Sporangia. 

 In Torrey Bulletin, XIII, 68, 69 (1886). 



Lyon (Florence May). Dehiscence of the Sporangium of 

 Adiantum pedatum. In Torrey Bulletin, Xiv, 180-183 (Sept. 

 1887). 



Atkinson (George F.). The Study of the Biology of Ferns 

 by the Collodion Method, 8vo. New York, 1894. (Macmillan 

 &Co.) 



CHAPTER VI. 



THE FERN ALLIES. 



Beneath my feet 

 The ground-pine curled its pretty wreath. — Emerson. 



A. THE GRAPE-FERNS AND ADDER-TONGUES. 



8 1 . General Characters. — These peculiar plants, former- 

 ly united with the order Filices, are now regarded as consti- 

 tuting a distinct botanical order. They include mostly small, 

 fleshy, terrestrial plants, and, like ferns, may usually be found 

 in swamps or rich, moist woods. As already noticed (5), there 

 is a marked tendency to variation in the same species, and 

 numerous varieties have been established from the various 

 forms. 



82. The sterile and fertile portions of the plant are borne 

 on a common stalk, and either portion may be sessile, long 



* See other references at close of Chapter X. 



