GEOGRAPHY OF CENTRAL FLORIDA 213 



mainly confined to the lake region, and are sometimes called bay- 

 heads. About half the trees in them are evergreen, and fire is rare. 

 They are little utilized at present, but will probably be drawn upon 

 for some kinds of timber when the country is more thickly settled. 



Calcareous szvanips. Swamps whose water is somewhat cal- 

 careous on account of coming from limestone springs or standing 

 for awhile in contact with limestone or marl differ from the sour 

 or non-alluvial swamps just described in having more deciduous 

 and usually larger trees, particularly cypress {Taxoduim- dis- 

 ticlmm). They have been described in the Third Annual Report, 

 pp. 271, 279-281, and Seventh, pp. 176-178. They are most com- 

 mon in the Gulf hammock and lime-sink regions, and in fact are 

 almost the only kind of swamps in those regions. They also occur 

 in the lake region, around some of the larger lakes and along the 

 Wekiva River and its tributaries. They grade into the low ham- 

 mocks to be described next, the only fundamental difference ap- 

 parently being the amount of water present. In the lake region they 

 often pass abruptly into saw'-grass marshes, on which they may 

 be gradually encroaching. Fire seems to be a negligible factor. 



The cypress is valuable for timber, but the other trees are com- 

 paratively unimportant. 



Low hammocks (fig. 25). Dense shady forests with soil per- 

 petually moist, but not quite wet enough to be called swamps, are 

 called low hammocks. Those in central Florida all seem to be more 

 or less calcareous, and they are especially characteristic of the Gulf 

 hammock region, but are quite common in the Ikke region and east 

 coast strip, and occur in most of the others. They have been de- 

 scribed in the 7th Annual Report, pp. 175-176. On the upland 

 side they often pass into semi-calcareous high hammocks (described 

 farther on), or even into sandy hammocks. Fire is very rare, as 

 in all other hammocks. 



Some of the trees are valuable for timber, and the soil is gener- 

 ally quite fertile, perhaps partly on account of washings from the 

 neighboring uplands; and where it can be easily drained it is often 

 cultivated in vegetables. Much if not most of the truck farming 

 in Seminole and Sumter Counties is in places formerly occupied 

 by this type of vegetation, and one of the largest orange groves 

 in the latter is in what seems to have been a low hammock, through 

 probably drier than the average. 



