200 PLANTS, SEEDS, AND CURRENTS 



we see at their best the capacities of the genus for dispersal. Yet 

 measured by the geographical range they have produced effects in 

 some inland species (species that could have owed but little to cur- 

 rents) which give the inland plants a rank near that of C. uvifera. 

 Thus, in Jamaica, out of nineteen species enumerated by Fawcett 

 and Rendle eight have been recorded from outside the island. Four 

 of them, excluding C. uvifera, are inland, and often mountain, species 

 that have a distribution in the West Indies nearly as wide as the 

 species just named, and three of the four reach the South American 

 continent. It is, therefore, apparent that currents have not endowed 

 C. uvifera with a much greater range than is possessed by some 

 inland species that could owe nothing to currents; and it is quite 

 likely that currents have not been the principal agent in its dispersal. 



Colubrina asiatica, Brongn. 



This littoral shrub is discussed at length in my book on Plant 

 Dispersal, and I have there dwelt on the suitability of its buoyant 

 seeds for dispersal by currents and on their occurrence in river- and 

 beach-drift in the Pacific islands. It is distributed over the warm 

 regions of the Old World including the African East Coast; but 

 I have found no reference to its occurrence on the West Coast. 

 Grisebach gives it as a West Indian plant, but for Jamaica only. 

 It should, however, be at once observed that not one of the several 

 other authorities consulted (Hemsley, Urban, etc.) mentions it as 

 occurring in the West Indies or in the New World, so that we seem 

 to have here the same difficulty that, as shown in a subsequent page, 

 is presented by Thespesia populnea. 



I found it in fruit growing abundantly beside a beach at Dry 

 Harbour on the north coast of Jamaica, where it was associated with 

 such characteristic strand trees and shrubs as Coccoloba uvifera, 

 Conocarpus erectus, Guilandina bonducella, and Suriana maritima, 

 and it was the most frequent of them all. The seeds are indistin- 

 guishable from those of the plant in the islands of the Pacific and 

 display similar floating powers. 



It may be that the difficulty lies in the species being very rare 

 in the tropics of America. The genus, which consists of twelve to 

 fifteen known species, is mainly American, a fact that in itself should 

 cause us to hesitate in excluding it from the New World, an opinion 

 expressed by the writer in his book on Plant Dispersal (p. 563) before 

 he visited the West Indies. As tested by him in Fiji, the seeds of this 

 species float unharmed in sea-water for many months, and they 

 are even better fitted for dispersal by currents than those of many 

 other littoral plants. There are, at least, two West Indian species, 

 Colubrina ferruginos a and C. reclinata, that are widely spread in that 

 region and may be found occasionally in littoral stations (Grisebach, 

 Urban, Millspaugh). 



We may add that Colubrina asiatica figures amongst the later 

 accessions to the flora of Krakatau, its seeds being derived from the 

 neighbouring coasts, where it thrives (Ernst). 



