TRANSACTIONS OF WAGNER 



VEGETATION OF SOUTH FLORIDA 



lantic coast from Cape Hatteras southward, there is a southward-setting cur- 

 rent,* which makes a gradual drift of silicious sand all the way down to Cape 

 Florida. Hence it comes about that the sands fill in on the northern side of 

 the inlet, and force the exit waters continually to widen the opening on their 

 south banks, a process which causes the inlets to move down the coast. 

 South of Cape Florida, Soldier Key begins the chain of Florida keys, where 

 the coral beaches of calcareous sand take the place of the silicious sand beaches 

 that extend north to Cape Cod. High dunes are characteristic of that part 

 of Florida about Jupiter Inlet, where the wind-blown sand is silicious. Low 

 dunes, or none at all, are characteristic of the coral beaches, because the cal- 

 careous sand lends itself to rapid solution by rain water and later the grains 

 may become rapidly consolidated into a tolerably firm mass, or rock. 



These coastal islands are separated by a number of inlets, which, be- 

 ginning with Indian River Inlet, are from north to south St. Lucie Inlet, 

 Jupiter Inlet, Lake Worth Inlet, Hillsboro Inlet, Ft. Lauderdale Inlet. 

 South of Cape Florida, where the coral beaches of the keys are found, the 

 passageways between the several islands are not designated on the coast map, 

 but the keys which concern this phytogeographic study are from north to 

 south Virginia Key, Key Biscayne, Soldier Key, Ragged keys, Sand Key, 

 Elliott Key, Old Rhodes Key, and Key Largo. 



The keys, which are considered only incidentally in this monograph, are 

 divided into four groups: The first group, called by Smallf the Upper Sand 

 keys, comprise Virginia Key and Key Biscayne, of silicious sand. The second 

 group, or Upper keys, consist of the keys that extend from Soldier Key to the 

 West Summerland, or Spanish Harbor keys. They consist fundamentally 

 of Key Largo limestone, and in the higher keys, dense hammocks are found. 

 They are of younger coral rock than the Lower keys, which consist funda- 

 mentally of Miami-Key West oolite, which forms the basic rock of the 

 ancient Miami keys, which are a part of the mainland. The fourth group of 

 the Lower Sand keys are composed of sand. They extend from the west- 

 ward of Key West out into the Gulf of Mexico, and their vegetation has been 

 investigated by Millspaugh.f 



* Cf . Shaler, N. S. : Beaches and Tidal Marshes of the Atlantic Coast. Physiographic 

 Processes, 1 : 153. 



t Small, John K.: Flora of the Florida Keys, p. iii. 



$Milhpaitgh, Charles P.: Flora of the Sand Keys of Florida. Botanical Series, Field 

 Columbian Museum, ii, No. 5, Feb., 1007. 



