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FREE INSTITUTE OF SCIENCE 
VEGETATION OF SOUTH FLORIDA 
103 
or groups of species, is conditioned solely by amount of space, light and edaphic 
influences. A very slight difference in the soil, drainage, depth below the 
general surface of the pineland, amount of soil, quantity of standing water 
and amount of light which penetrates between the pine trees makes a striking 
difference in the composition of the vegetation of these banana holes. That 
such slight differences of environmental conditions influence the character of 
the vegetation is demonstrated by that of the snow patches found in the Euro- 
pean Alps. These snow patches are, according to C. Schróter,* gently in- 
clined flat, or concave spots that occur in the Alps and are saturated with 
water from melted snow. If they exist as depressions filled with snow for a 
long time, then there is deposited thick, black humus which owes its origin 
to the snow. For this carries down from the air a quantity of organic dust, 
wind-blown particles gather here, and the snow is thus made a catch-all 
for such extraneous bodies. This habitat is characterized by lowness of 
temperature, abundance of humus and permanent saturation of the soil. The 
community of plants settling upon it in Switzerland is extremely constant. 
Similarly the limestone sinks in South Florida receive a large amount 
of material washed into them from the surrounding pineland. These 
materials consist of sand, and minerals leached out of the exposed surface 
oölite, while in addition leaf mould, small branches, pine cones, etc., are 
swept into the pot-holes and collect like the material does in the vortex of 
water which rushes from a paved street of a city down into a grated culvert 
provided to catch the surface run-off. Then too the herbaceous vegetation 
of such sinks is protected in the bottom from sharp winds which visit South 
Florida, and from the too direct rays of sunlight. Such concave spots are 
usually moister, so that filmy fernsf (Hymenophyllacez) are found growing 
along their edges, while epiphytic orchids, ferns and bromeliads live attached 
to the trees above. Many shade-loving plants find a suitable habitat here, for 
the sunlight, first cut off by the surrounding pine trees, must pass the tree and 
shrubby growth which fills the banana holes and receive an amount of light 
conditioned by the depth of the well below the general surface of the pineland. 
Origin of Banana Holes and Hammocks.—As the banana holes exist in all 
sizes from those which can be jumped across to those covering one hectare, a 
sharp distinction cannot be drawn between the vegetation of the larger banana 
holes and the smaller hammocks which occur in the same region. For example 
* Warming, Eug.: Ecology of Plants: 319. On the authority of Ernst Bessey. 
