144 IN LOiVER FLORIDA fVILDS 



rivers. The slowly advancing wall of ice and the 

 cold temperature drove the flora southward. 

 We have in Lower Florida at least seventy-five 

 species of plants which also range north to or 

 beyond the fortieth parallel, some of which reach 

 even into Canada. These probably had fled before 

 the oncoming glaciers in the north but finding here 

 conditions favorable for .their growth, they re- 

 mained and became a permanent part of our flora. 

 Some of these have continued their range into the 

 West Indies and a very few, such as the common 

 reed and cattail, have a still wider distribution, 

 even including the Old World. It is therefore 

 impossible to be sure in every case whether a 

 species originated in the north, the American 

 tropics, or in the Orient. 



It is probable that before the glacial period, a 

 warm temperate or semi-tropical flora inhabited 

 the region of our present Southern States and a 

 more strictly tropical one the lower part of Florida. 

 The cold of the ice age exterminated the tenderer 

 plants, for although there was no actual ice cap in 

 the Southern States, the many years of continu- 

 ous winter materially lowered the temperature 

 throughout the south. Some Florida remnants 



