TRANSACTIONS OF WAGNER 

 06 



VEGETATION OF SOUTH FLORIDA 



highest portions were entirely under water. On a drive from Ft. Myers to 

 Six Mile Cypress, 13 kms. (8 miles) south of that town, the horses waded the en- 

 tire distance in 30 1045 cms. of water. The plants of the fourth layer were en- 

 tirely submerged and those of the third layer partially so. Many of the 

 plants were collected with open flowers entirely beneath the surface of the 

 clear rain water. There are times, therefore, when the soil of the pineland for 

 several weeks at a time may have a surfeit of water. That the wide distribu- 

 tion of many of the typic pine forest species is due to water rather than to other 

 agents, such as winds and animals, is probable. Such floods rarely have the 

 disastrous effects on the soil surface that they would have in a country of more 

 considerable elevation and rapid run-off. 



The movement of water in South Florida after such an inundation, except 

 in the larger rivers where there is a considerable current, is never rapid. The 

 surplus water gradually drains away along old and well established drainage 

 channels and the remainder passes rapidly from the surface soil into the under- 

 ground channels by percolation. It does not take long, therefore, for the coun- 

 try to dry up, but in this process with hot suns the surface may steam for several 

 days. The effect of this steaming operation on plants has never been investi- 

 gated, nor has the effect of the rapid alternation from dry to wet and wet to 

 dry. That the xerophytic structure may be induced by these factors, as well 

 as those of dry soil, intense insolation, etc., is possible, but in the absence of 

 instrumental, or experimental, proof, one cannot be dogmatic. That the forma- 

 tion of flowers and fruits is influenced by such extreme flooding can be demon- 

 strated. If the flowers are submerged at the critical period of pollination, no 

 fruits will be formed. If the submergence occurs when the flower buds are 

 ready to open, such an annual occurrence may be arrested, or entirely stopped. 

 If the inundation comes when the green fruits are beginning to ripen, such a 

 process may be inhibited completely. As in other regions, it is the critical 

 periods of the climate and environment, which test the efficiency of the adapta- 

 tions of plants, and it is these conditions, which control the successful establish- 

 ment of plants in different parts of the world. Many plants from other parts 

 of the country make a start in South Florida, but the porous soil, the winter 

 droughts, the heavy rainfall of summer and autumn, the winds, the occasional 

 dry hurricanes and the occasional inundations are limiting factors to many of the 

 new forms introduced into the region and they fail of establishment. 



