THE PLANTING OF OUR FLORA 147 



The Everglades stretch almost across the 

 northern part of Lower Florida like a line of forti- 

 fications forbidding entrance to dry -land plants of 

 the warm temperate region. According to the 

 map of the Everglades Drainage District the great 

 swamp comes out to the Gulf of Mexico in the 

 neighborhood of Chatham River and extends 

 south along the Ten Thousand Islands to Cape 

 Sable, but there is at least one considerable body 

 of hammock land along Rodgers River. At any 

 rate the immigration of the more northern dry- 

 land plants is prevented on the west and they can 

 only enter the lower part of the State along the 

 sandy, rocky ridge near the east coast. The seeds 

 of a few like the thistles and other Compositas may 

 have been wind-borne from the northward. 



All the tropical part of our flora has migrated 

 in some way across the sea; even the seeds of 

 Cuban plants must have crossed a strait at least 

 ninety miles wide. The question of how they 

 reached our shores and became established is a 

 very interesting one. 



It has been claimed that a land passage con- 

 nected Cuba and the lower end of Florida within 

 the lifetime of our existing plants and animals, but 



