Combs — Plants Collected in the District of Cienfuegos. 397 



as these winds occur in winter, Cuba's dry season, the seeds 

 could hardly establish themselves for want of favorable con- 

 ditions, and when the rainy season comes, in May, they could 

 not contend with the luxuriant tropical plants already 

 established there. 



But, if the migration is so decidedly from south to 

 north in this region, the question might well be asked: 

 Why does not the neotropical flora become established io 

 Florida? That it does not, is due partly to the fact that the 

 Gulf Stream flows rapidly in the straits of Florida, and, 

 when it leaves the straits it quickly diverges from the coast, 

 thus throwing all its influence on the Bahamas instead of on 

 Florida, as might at first be supposed. It is also due in part 

 to the inability of the tropical plants to contend with tem- 

 perate ones on their own ** native heath." 



The great difference between the Cuban and Floridan floras 

 is beautifully accounted for by considering the original birth- 

 place of plants to have been somewhere in the northern 

 hemisphere, and that they then by migration came south, 

 part going to Florida, where they stopped, part going down 

 the continent through Mexico into Central and South America, 

 and thence turning north, along the lines of the now sub- 

 marine banks, into Cuba. This would make the Floridan flora 

 much the oldest and most general, while the Cuban would be 

 an extreme. 



The distribution of the flora over the island is very interest- 

 ing. The many different kinds of soil, the altitude, the 

 proximity to the sea, all combine to make a constantly vary- 

 ing or changing flora, which might be likened by an enthusiast 

 to a great panorama. 



We have, 1st, the maritime region, the plants of which 

 vary with its character, according to whether it is rocky 

 cliffs, rocky reefs, long sandy beaches, sand hills, salt marshes, 

 or mangrove swamps; 2d, the river bottoms, gradually dif- 

 ferentiating from the maritime as they ramify in the island j 

 3d, the inland swamps, or ** cienegas," derived from the 

 maritime; 4th, the upland woods, varying with the soil and 

 moisture ; 5th, the mountain region, the plants varying with 

 altitude, proximity to sea, etc. ; 6th, the savannahs or wooded 



