244 PLANTS, SEEDS, AND CURRENTS 



land and sea as it is at present, the distribution of this tree offers 

 one of the most difficult problems dealt with in these pages. 



Thespesia populnea, Corr. 



This tree has presented itself to me as a littoral plant in several 

 parts of the tropical zone, namely, in Hawaii, Fiji, the Solomon 

 Islands, Keeling Atoll, and in different islands of the West Indies. 

 Its distribution over the tropics of the Old World and its mode of 

 dispersal by currents are discussed in my book on Plant Dispersal ; 

 but I did not there regard it as belonging to the New World, being 

 guided in this matter by Bentham, who in his Flora Australiensis 

 regards it as introduced into America. However, there can be 

 little doubt that it behaves in the West Indies as an indigenous 

 plant ; and, considering its great capacity for dispersal by currents, 

 there seems in the light of more recent investigations but small 

 reason for the refusal of its proper place in the flora of the New 

 World. " Quod credere vix possum " is Urban' s opinion concerning 

 the belief of botanists that it has been introduced into America (Symb. 

 Antill., IV., 401). If the distribution of the genus given in the Index 

 Kewensis offers a clue, the New W T orld can almost make an equal 

 claim to be the home of this tree. Of the seven other species there 

 named, three are peculiar to Mexico, the West Indies, and Brazil, 

 respectively ; one is only found in Africa ; and three are confined to 

 Malaya. It is, however, quite possible that in some distant age 

 the tree reached the New World from tropical W^est Africa, where 

 it is now at home, since the seeds could have been readily carried 

 across to Brazil in the Main Equatorial Current. 



It is distributed over the Greater and Lesser Antilles and is found 

 in Trinidad (Hart). I especially observed it in St. Croix, Jamaica, 

 Grenada, Tobago, and the Turks Islands. In order to prove that 

 it behaves as an indigenous shore tree in the West Indies it is of 

 importance to name its associates. I found it thriving at the beach 

 border on St. Croix in the company of such characteristic littoral 

 trees and shrubs, as Coccoloba uvifera, Guilandina bonducella, and 

 Hippomane mancinella. Harshberger states that on St. Croix and 

 the Virgin Islands it is one of the Coccoloba-Hippomane association, 

 the formation of trees and shrubs that immediately lines the beaches 

 (p. 686). 



Grisebach speaks of it as growing along the sea-coast of Jamaica, 

 and I made notes of its associates in different localities on the shores 

 of that island. On the beaches of the Black River district it was 

 associated with Coccoloba uvifera, Ecastaphyllum brownei, and 

 Guilandina bonducella. In the Savanna-la-mar district a mangrove 

 fringe often skirts the low sandy shores, and on the beach behind 

 it this tree thrives in the society of Guilandina bonducella, Coccoloba 

 uvifera, and Conocarpus erectus, one of the most typical strand 

 shrubs of the West Indies. It is associated with the same three 

 plants on the borders of the beaches on the north side of the island, 

 as at St. Anne's Bay and at White River, and to them we may 

 add Sophora tomentosa, another characteristic beach shrub. With 

 Coccoloba uvifera it is one of the commonest of the plants bordering 



