FREE INSTITUTE OF SCIENCE 



VEGETATION OF SOUTH FLORIDA 



97 



The rainfall at Miami, according to the records of the U. S. Weather 

 Bureau, has been for a period of thirteen years, as follows : 



AVERAGE MONTHLY RAINFALL 



AVERAGE NUMBER OF RAINY DAYS 



Although the rainfall equals in quantity that of many other regions, yet 

 in South Florida, as seen from the figures above, it is unevenly distributed 

 throughout the year. The summer season is wet, the winters are usually clear 

 and very dry. The conditions then are droughty. During the heaviest rainfall 

 of summer, tender crops are beaten to the ground by the pelting force of the 

 wind-blown rain, and a hard shower followed by a hot sun does considerable 

 mischief. Another ecologic factor of considerable importance in South Florida 

 is the wind. The prevailing winds are from the east and despite the fact that 

 they blow from the ocean, they are dry winds. Occasional dry hurricanes 

 blow from the south and tender vegetation is blackened and parched. The 

 effect of the dry hurricane is similar to the desert sirocco of the Mediterranean 

 region. The influence of these several factors accounts for the xerophytism 

 of many South Florida plants. 



Frost is another inhibiting factor. Occasional frosts of short duration 

 visit the extreme southern end of Florida, so that tender plants are injured here 

 and there. But these slight touches of frost in winter and the cool nights with 

 a temperature occasionally near the frost point hardly influence the native 

 vegetation of the region. The following is a table of the lowest temperatures 

 in degrees Fahrenheit on record at Miami, interesting, especially as to winter 

 conditions: 



We have noted previously that the silver palm, Coccothrinax argentea 

 (Plate II, Fig. 3) near Miami is about i meter tall, but farther south near Home- 



