1920] The Land of Ferns 95 



islands. The ver^- gradually sloping ocean bottom acts as a barrier 

 against the approach of high waves from the Gulf of Mexico. The 

 long-leaf pine is the most abundant tree, but there are many low ham- 

 mocks besides the great Gulf Hammock of Levy County — whence the 

 name for the region. 



The vast majority of the species comprising this fern flora are na- 

 tive plants that occur also outside the state, either in the eastern 

 United States or in tropical America. They fall into two groups : 

 the one composed of northern elements, the other of southern elements. 

 With very few exceptions the plants are tibrous-rooted. The species 

 of the genera Botrychium, Ophioglossum, and Cheiroglossa are fleshy- 

 rooted and doubtless all represent mycorrhiza forms. 



The northern elements comprise about one-third of the species. 

 They are not, however, all strictly typical of decidedly northern lati- 

 tudes. On the one hand, some only extend northward as far as south- 

 ern Georgia, and others are merely in the coastal plain of the Gulf 

 of Mexico, while on the other hand a few of the species that are 

 naturally included among the northern ferns are found in the Amer- 

 ican tropics. Following is a list of the species: 



Botrychium obliquiuu (Grape-fern) 

 Botrychium virginianum (Rattlesuake-fern) 

 Ophioglossum vulgare (Adder 's-tongue) 

 Ophioglossum crotalophoroides 

 Trichomanes Bosehiauum (Filmy-fern) 

 Osmuuda regalis (Eoyal-fern) 

 Osmunda cinnamomea (Cinnamon-fern) 

 Lygodium palmatum (Climbing-fern) 

 Pteris aquilina (Brake) 



Adiantum Capilhis-Veneris (Venus 'hair fern) 

 Pellaea atropurpurea (Cliff -brake) 

 Anchistea virginica (Chain-fern) 

 Lorinceria areolata (Chain-fern) 

 Asplenium platyneuron (Spleenwort) 

 Asplcnium resiliens 

 Athyrium Filix-foemina (Lady-fern) 

 Dryopteris Thelypteris (Shield-fern) 

 Dryopteris floridana (Wood-fern) 

 Dryopteris hexagonoptera (Beech-fern) 

 Polystiehum acrostichoidcs (Christmas-fern) 

 Onoclea sensibilis (Sensitive-fern) 

 Marsilea vestita (Pepperwort) 

 AzoUa caroliniana (Watcrmoss) 

 Lycopodium alopecuroides (Clubmoss) 



