Origin of the Pteridophyte Flora of the Bahamas, Caicos and Turks Islands

Abstract

The region under consideration might be likened to the open mouth of a vast sack of tropical and subtropical plants of all categories. It is a region, excluding Bermuda, that is occupied by the farthest northeastward extension of floristic elements which have their optimum development to the south (in Cuba, Hispaniola, and Puerto Rico) and west (in Florida). Subtropical southern Florida and its keys also have been recipients of the Greater Antilles flora. According to the best authorities, the geological processes of emergence and subsidence have affected the low-lying Bahamas more than once in the past. During periods of greatest emergence, the islands of the relatively shallow Little Bahama Bank (primarily Grand Bahama and Abaco) were connected. The same is true of the islands of the Great Bahama Bank (primarily New Providence, Eleuthera, Cat, Exuma, Long and Andros). However, the great depth of water between the two banks has precluded their ever having been connected. All of the islands scattered to the south of the Great Bahama Bank also have such depths of water between them that apparently they have never been connected; the main islands in this group are San Salvador, Crooked, Acklin, Mariguana, Inagua, Caicos and Turks. Finally, the great depth of water between all of the above islands and Florida, Cuba, and Hispaniola would appear to have prevented their ever having been connected, except for a possible connection of Great Bahama Bank with Cuba during the last Ice Age, about 25,000 years ago. That connection would account for some of the animal life now known to occur on some islands in