TRANSACTIONS OF WAGNER 

 78 



VEGETATION OF SOUTH FLORIDA 



ized by wart-like lenticels and on them cling oysters and a large amount of float- 

 ing material, while mud and sand carried by ocean currents are deposited among 

 the intricate complex of roots, and gradually the shore line advances seaward. 

 While the foliage of the red-mangrove is dark-green and lustrous, that of the 

 black-mangrove is of a grayish-green color. The latter is a low spreading tree 

 found on the tidal flats out of the muddy soil of which the pencil-thick, aspara- 

 gus-like pneumatophores project. These vertically directed root branches 

 may be submerged with the rising tide, or may be in drier situations exposed 

 constantly to currents of air. 



The mangrove formation was studied at a number of localities in South 

 Florida. Back of Fairyland Beach, opposite Miami, and along Bay Biscayne, 

 we find the shore fringed with red-mangrove, Rhizophora mangle L., associated 

 with the black-mangrove, Avicennia nitida Jacq. The flat tidal, more open 

 areas are characterized by the spreading, prostrate, pale-green patches of the 

 saltwort, Batis maritima L. The light-green of this low, woody plant con- 

 trasts strongly with the dark green of the overhead mangrove foliage. The 

 buttonwood, Conocarpus erecta L., is found as an element of the inner edge 

 of the thicket, as well as Baccharis angustifolia Michx., while along a line where 

 the swamp meets the higher ground it is bordered by a low shrub, Borrichia 

 frutescens (L.) DC. and clumps of a sedge, Fimbristylis Harperi Britton. 



The mangrove vegetation that lines both banks of the Miami River 

 (Plate I, Fig. 2) up to its fork, where the swift current has laid bare the lime- 

 stone rock where the mangrove hardly maintains itself, consists of the dom- 

 inant red-mangrove, Rhizophora mangle L., black-mangrove, Avicennia nitida 

 Jacq., and buttonwood, Conocarpus erecta L., with which are associated the 

 red-berried dahoon, Ilex cassine L., the cocoa-plum, Chrysobalanus icaco L., 

 Baccharis angustifolia Michx. and B. glomeruliflora Pers. The mangrove 

 border, which is not over 50 feet wide, is not a continuous strip, but is broken 

 by grassy stretches and by areas dominated by the cat-tail, Typha angustifolia 

 L. A tall fern with heavy fronds, Acrostichum aureum L., is conspicuous as 

 a mangrove species. An aquatic plant, Sagittaria lancifolia L., becomes more 

 common along the shore as the mangrove clumps become less frequent. Saw- 

 grass, Cladium effusum (Sw.) Torr. [=Mariscus jamaicense (Crantz) Britton], 

 Typha angustifolia L., and Rhizophora mangle L., alternate with each other. 

 A species of bladderwort, Utricularia oligosperma St. Hil., floats on the water 

 in front of the low mangrove trees at the fork of the river. 



The mangrove formation along Billy Creek, a stream which empties 



