1920 | Tuer Lanp or FERNS 95 
islands. The very 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 fibrous-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 obliquum (Grape-fern) 
Botrychium virginianum (Rattlesnake-fern) 
Ophioglossum vulgare (Adder’s-tongue) 
Ophioglossum crotalophoroides 
Trichomanes Boschianum (Filmy-fern) 
Osmunda regalis (Royal-fern) 
Osmunda cinnamomea (Cinnamon-fern ) 
Lygodium palmatum oe 
Pteris aquilina (Brake 
Adiantum nt Naat (Venus’-hair fern) ® 
Pellaea atropurpurea (Cliff-brake) 
Anchistea virginica (Chain-fern) 
Lorinceria areolata (Chain-fern) 
Asplenium platyneuron (Spleenwort) 
AR ae ieee 
Dryopteris hexagonoptera (Beech-fern) 
Polystichum acrostichoides (Christmas-fern) 
Onoclea, sensibilis (Sensitive-fern) | 
Marsilea vestita (Pepperwort) 
Azolla caroliniana (Watermoss) 
Lycopodium alopeeuroides (Clubmoss) 
