FREE INSTITUTE OF SCIENCE 



VEGETATION OF SOUTH FLORIDA 



pineland with slash-pine, Pinus caribaea Morelet. This sand region extends 

 from the north side of Indian River Inlet south to Hillsboro Inlet, and it con- 

 sists of fine wind-blown sand derived from the sand deposited along the coast 

 by the southward-moving oceanic currents. The evidence of this wind action 

 is seen in the ancient dunes, or ridges, related in origin to the coastal dunes. 

 The sand deposits have covered an older, flat land of limestone, which is seen 

 in the valleys, or swales, between the ridges and along the Everglades, where 

 the monotonous level of the flatland and the prairies denotes the earlier surface. 

 The flat lands with their covering of slash-pine, Pinus caribaea Morelet, are older 

 geologically and their vegetation is older to the region than that of the rolling 

 sand hills and sand plains with their covering of sand-pine, Pinus clausa 

 (Engelm.) Vasey. As far as the evidence at hand will permit one to judge, the 

 encroachment of the coastal sand deposits caused the destruction of the pine 

 forests and vegetation of the older flat limestone surface by wind-blown sand. 

 Subsequent to this period, the sand pine vegetation gradually spread over the 

 inland deposits of dune sand. The original land surface is also determined by a 

 study of the lakes, several miles long, that occupy depressions in the older 

 limestone land. The possible maximum width of the sand deposits in east 

 Florida is not over 9 kilometers. 



The dominant tree of this region is the sand-pine or spruce pine, Pinus 

 clausa (Engelm.) Vasey, not over 6 to 9 meters tall and with its stem in some lo- 

 calities, as at Palm Beach, inclined to the west, because of the prevailing east 

 winds (Plate II, Fig. 2). This tree with relatively smooth bark is branched 

 close to the base with spreading, or upward directed branches, and in its habit of 

 growth it suggests the scrub-pine or Jersey pine, Pinus virginiana Mill. The 

 crown of the sand pine is a fairly close one. The stand may be dense in some 

 spots and in other places wide-spread, so that plenty of sunlight reaches the 

 forest floor. The intolerant pines form the upper story in an exclusive or pure 

 stand. The tolerant species that form the second story are several evergreen 

 oaks which remain as shrubs and small trees beneath the shade of the pines. 

 A low oak, Quercus geminata Small, with pale-gray, furrowed bark, is a conspic- 

 uous element, but as a suppressed growth, it never reaches above the crown 

 of the spruce pines. As a shrub, it has narrowly oblong, elliptic, or oblong- 

 lanceolate, revolute-margined, leathery leaves and is an important part of 

 the undergrowth of the rosemary scrub. Another much-branched evergreen 

 shrubby oak is Quercus myrtifolia Willd., with a smooth bark and leathery 



