FREE- TNS DU TE OF SCIENCE 
VEGETATION OF SOUTH FLORIDA 
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along Alligator Creek, Miakka River, Rocky Creek, Peace Creek and Joshua 
Creek. The exact location of these deposits is given on the excellent geo- 
logic map of the state published in the Second Annual Report of the Florida 
State Geological Survey. 
This general geologic account of the southern end of the Florida peninsula 
will serve to orientate us with respect to the time at which the existing land, 
soil and rock strata appeared. It will also enable us to connect the geographic 
character of the country with its geologic structure. The details that have 
been omitted in the general account will be emphasized when we discuss the 
plant formations and associations, as their geographic distribution is influ- 
enced by the edaphic conditions of the country. 
PHY TOGEOGRAPHY 
South Florida is a region of unusual phytogeographic interest. The 
climatic conditions are fairly uniform, so the environmental factors, which 
are considered as climatic, influence all plants much in the same way. The 
edaphic conditions, which include the character of the soil and the amount 
of water in the soil, are more important in the allocation of plants to certain 
habitats than are the climatic factors. South Florida is a country of little 
relief and its flat surface, although varying to some extent in altitude above 
sea level, shows change in level from place to place always as a gradual and 
sometimes imperceptible one. A few centimeters difference in level will bring 
about an entire change in the water-holding capacity of the soil, and, there- 
fore, an entire change in the vegetation. ‘The lines of demarcation between 
the different plant formations and associations are sometimes very sharply 
drawn. For example, a person can stand with one foot in the pine forest and 
the other in a prairie glade (Plate X, Fig. 2), indicating that the line of separa- 
tion between hammock and pineland is in many places very distinct. The 
soil varies from locality to locality. Near Delray are extensive inland sand- 
hills in the pure silicious sands of which certain associations of trees are found 
(Plate II, Fig. 2). The pineland of the area underlaid by the Miami-Key 
West oölitic limestone differs from that of the sandhills (Plate II, Fig. 3), 
while the vegetation of the Everglades is related to other marsh vegetation in 
North America. 
The phytogeographer can distinguish a larger number of plant formations 
