1920] THe Lanp or FERNS 103 
hanging rocks with rather smooth faces the plants are often scattered. 
Most of the kinds grow not only on the perpendicular faces of the 
rocks, but also on the top of boulders and all more or less horizontal 
surfaces. The masses of leaves of all sizes and kinds of ferns often 
completely hide numerous pitfalls of various sizes and ranging from 
a few feet to twelve feet deep. Walking is rendered exceedingly 
dangerous from these treacherous pitfalls alone, not to mention the 
soft and crumbling edges of cliffs and ledges. 
Among the tropical ferns that do not comply with our rule of these 
three tropical phytogeographie areas, are the amphibious leather-ferns 
(Acrostichum), which extend northward along the coastal strip or 
through the Everglades up into the Lake region, the floating-ferns 
(Ceratopteris) which are scattered through the peninsula up into the 
Lake region, and such epiphytes as the hand-fern (Cheiroglossa), the 
serpent-fern (Phlebodium), the vine-fern (Phymatodes), the shoe- 
string fern (Vittaria), two species of strap-fern (Campyloneurum), 
and the sword-fern (Nephrolepis). 
The exception in the ease of the epiphytes, however, is easily ac- 
counted for. The soil or rock conditions in the country lying between 
southern Florida and the northern part of the peninsula are wanting, 
but whenever the conditions of hammocks in this intervening territory 
are favorable, for example, the hammock on the eastern shore of 
Okeechobee, these epiphytes, finding congenial conditions, take hold 
and thrive. 
There are nine kinds of ferns common to the Everglade Keys and 
to the lime-sink region. They are of tropical origin. There are forty- 
two species growing on the Everglade Keys not yet found in the lime- 
sink region, and five species have been collected in the lime-sink region 
not yet met with on the Everglade Keys. 
Travelers and botanists observed and perhaps collected specimens 
of ferns in Florida before the beginning of the Eighteenth century. 
Then during the earlier part of the last century, further collections 
were made in many localities, and about the middle of that century 
nearly fifty species of ferns were known to grow wild in the entire 
State. During the eighth and ninth decades of the last century and 
Shor sas more detailed Baal of these fern grottoes see H. Curtiss, Plant World 
5: 68-70, 1902, and R. M. Harper, American Fern Journal hg "68-81, 1916. 
