TRANSACTIONS OF WAGNER 
102 : 
VEGETATION OF SOUTH FLORIDA 
others have been formed by gradual solution and by the falling of roofs of 
subterranean water courses. Few of the holes are large enough to be 
termed sinks. The vertically walled banana holes extending down to per- 
manent water level form natural wells, the shallow hollows are best termed 
pot-holes. С. C. Matson and F. С. Clapp* of the Florida Survey, estimate 
that the rate of solution in the limestone section of central Florida is about 
400 tons per square mile annually. If evenly distributed, this would lower the 
surface of the limestone about three decimeters in five or six thousand years. 
The soil which fills these rock basins is a sandy loam and rich in organic 
matter owing to the collection of vegetal material formed partially under 
standing water. The edge of these sinks may be a rock rim with vertical 
sides, or it may blend by gradual slope with the rock surface of the surrounding 
pineland. These depressions have been formed probably in irregular areas 
of softer oólite which, less resistant to the solvent action of rain water, has 
been removed by gradual solution. These pot-holes in South Florida with 
their characteristic vegetation suggest the limestone sinks in Bermuda, which 
are filled with a vegetation quite distinct from the cedar-covered hillsides. 
The “Cockpit Country" in Jamaica is a region of limestone sinks, but in a 
mountainous country and on a far grander scale. 
Ecologic Considerations.—It is noteworthy that a slight difference of eleva- 
tion makes an entire difference in the vegetation of South Florida. A difference 
of twenty to forty centimeters may mean a change in the plants which enter 
into any particular plant formation. Here under practically the same climatic 
conditions we find plant formations which owe their character to the con- 
trolling edaphic, or soil conditions. Here on a scale not found elsewhere 
in North America, the ecologist can study the influence of varying amounts 
of soil water on the native vegetation of the country. 
The banana holes (Plate III, Figs. 1 and 2), as depressions in the flat 
woods, owe their ecologic character to their size, the character of their soil, 
richer or poorer in humus and the presence, or absence, of standing water dur- 
ing the whole, or a part of the year. In wet weather some of these pot-holes 
are filled with water, but during dry weather, the water disappears by seep- 
age, or by rapid evaporation. The occupancy of these banana holes by the 
migration of plants, is purely fortuitous,] but the survival of any one species, 
* Matson, G. C., and Clapp, F.G.: Second Annual Report, Florida State Geological Survey, 
1908-09: 34; Cf. Geikie, Archibald: 'Text Book of Geology (third edit.): 344. 
1 See what follows under heading Means of Distribution." 
