THE ORIGIN OF THE HAMMOCKS 205 



mock the broad-leaved growth has been entirely 

 exterminated, and one can only know it for an 

 ancient hammock site by the presence of half 

 burned or decayed logs, or by broken fragments 

 of the tree snails scattered on the surface or 

 buried in the ground. Rarely a small hammock 

 may be found on high land which has no sink 

 or depression as a nucleus, but the few I have 

 seen were near other larger hammocks and doubt- 

 less had been cut off from them by fire. The 

 damp hammock sinks instead of being overgrown 

 with coarse vegetation, as in the open pine woods, 

 are made ravishingly beautiful by the ferns and 

 other shade and moisture loving plants that 

 occupy them. No words that I can summon 

 will properly describe the wonderful effect pro- 

 duced by these fern gardens. The ferns often 

 scramble up the tree trunks, covering them with a 

 delicate mat to a height of several feet. Here is 

 found the only tree fern of the United States, 

 Dryopteris ampla, with richly cut fronds spread 

 over a space of a dozen feet and supported on stout 

 trunks two feet high. The walls of the larger 

 sinks are often covered with elegant halberd ferns 

 and from among them spring immense tufts of 



