TRANSACTIONS OF WAGNER 



VEGETATION OF SOUTH FLORIDA 



HIGH HAMMOCK FORMATION 



A hammock from the standpoint of the physiognomy of the vegetation 

 is a group of hardwood trees, shrubs, vines, terrestrial and epiphytic herbs 

 scattered as islands about the country, usually in a rather deep soil, rich in 

 humus, or vegetable matter, and more retentive of water than the adjacent 

 pineland (Plate V, Fig. 2). The growth is generally so crowded that the 

 vines, epiphytic ferns, orchids, and bromeliads are found in every available 

 light space. Small described a hammock which was being destroyed by the 

 excessive development of epiphytes, which took possession of every available 

 bit of surface until by their weight the trees were thrown to the ground. The 

 broad leaf canopy is so thick by the interlocking of the upper branches of the 

 trees that the shade beneath the trees is very dense and even at midday a 

 twilight prevails beneath the dominant trees. Only those plants can exist 

 beneath the trees that are tolerant, and the absence of a rich herbaceous under- 

 growth is a marked feature of the larger hammocks, and the leaf litter, which 

 collects at times, rapidly disintegrates and the forest floor is, therefore, a re- 

 markably clean one. The vegetation consists mainly of large trees, small 

 trees, shrubs, lianes, and epiphytes. The hammock vegetation includes the 

 great majority of flowering plants now known to be common to the West 

 Indies and Florida. The area occupied by the hammocks is insignificant, as 

 compared with that of the pineland, yet there are nearly as many species of 

 flowering plants growing in these small areas, as there are in the vast pinelands. 



In a preceding part of this paper, I have referred to the probable origin of 

 the hammock vegetation in a way similar to that of the smaller pot-holes. 

 That is, the broad-leaved hammock plants appear in depressions of the surface 

 which gradually fill with an abundance of humus, so that a rich, sandy loam is 

 formed in which this peculiar type of vegetation is perpetuated. Near 

 Detroit, the last settlement on the eastern coa^t of the mainland of Florida, 

 occur two hammocks, which according to my observations have had their 

 origin in large depressed areas, or extensive pot-holes. The smaller one is 

 characterized by live-oak trees, *Quercus virginiana L., with large twisted 

 branches supporting epiphytic ferns, *Polypodium polypodioides (L.) A. S. 

 Hitchcock, bromeliads and orchids, such as Epidendrum rigidum Jacq., 

 associated with an evergreen tree, Dipholis salicifolia (L.) DC., palmettos, 

 *Sabal palmetto (Walt.) R. & S., Tetrazygia bicolor Cogn., cocoa-plum, 



* Indicates species common to hammocks and banana holes. 



