A 
FREE INSTITUTE OF SCIENCE ^i 
VEGETATION OF SOUTH FLORIDA "73 
the pine forest. At another place beyond Detroit, a hammock touches the 
open prairie with its sclerophyllous vegetation (Text Figure 1). The prairie 
is dotted with islands of bushes and low trees and Small considers it to be 
a part of the Everglades. There are differences, however, which lead one to 
consider the coastal prairie a distinct phytogeographic formation. The coastal 
prairie is influenced by salt water. Several miles south of the pineland, the 
surface of the prairie is sprinkled with low mangrove bushes, Rhizophora 
mangle L., raised on stilt-like roots and with round-headed tops of light-green 
foliage, and the presence of this tree phytogeographically makes the coastal 
prairie a formation distinct from the Everglades proper (Plate II, Fig. 1). 
As the botanist approaches the coast of the Bay of Florida, where the rail- 
road leaves the mainland for the Florida keys, the red-mangrove trees become 
larger and more closely set together until when the shore is reached they form 
a continuous fringe along the coast. From the tests made of Miami River 
water with the hydrometer in the midst of the mangrove vegetation, it would 
appear that the red-mangrove will grow in fresh water, hence it is not fresh 
water that reduces its size in the coastal prairie. Here it is surrounded with 
the saw-grass and other grasses that form a close sod or compact root system, 
the mangrove is finally suppressed, when the prairie vegetation becomes 
absolutely dominant. It would appear that with the advance of the southern 
coast of Florida by the encroachment of the mangroves upon the shallow bays 
the prairie vegetation follows the advance of the mangroves in natural suc- 
cession, and as rapidly as the prairie conditions prevail the mangrove trees 
become reduced in size and finally are suppressed.* Some of the hammocks 
scattered over the prairie have such component species as tall palmettos, 
Sabal palmetto (Walt.) R. € S., waxberry, Cerothamnus (Myrica) ceriferus 
(L.) Small. At the southern end of the prairie, the surface is intersected by 
channels of water and the prairie islands are replaced by mangrove-covered 
islands. 
The plants collected by the writer on the coastal prairie at Detroit are 
scattered over the surface and are not found in pure association. It is by this 
commingling of species that the surface soil is covered by a dense mass of 
the following plants: 
* Harper suggests that the succession may be in the other direction, viz., the invasion of the 
prairie by mangrove trees. 
