MISCELLANEOUS PLANTS 



219 



for the existence of this plant in the Azores, the seeds must have come 

 in the Gulf Stream drift in the company of the other West Indian 

 seeds thrown up on these islands. It is true that the Mediterranean 

 shores would offer a much nearer source ; but the current connections 

 do not allow us to appeal to that region. It is, however, possible, 

 as implied by Dr. Millspaugh in the case of Cakile edentula, its com- 

 panion on the beach of Porto Pym, that it may have been introduced 

 with ballast. But the same suspicion would fall on the other beach 

 plants of this little bay, Polygonum maritimum, Salsola kali, Euphorbia 

 peplis, etc. That West Indian seeds are sometimes stranded there 

 is indicated by my finding on the same beach a seed of Sapindus 

 saponaria apparently in a sound condition. 



Ipomcea pes-capr^:, Sw. 



Since this wide-ranging tropical beach plant has been discussed 

 in detail in my book on Plant Dispersal in the Pacific, I will restrict 

 my remarks mainly to its occurrence in the West Indian region. 

 The circumstance that it came under my notice in Jamaica, Turks 

 Islands, St. Croix, Grenada, and Tobago, as well as at Colon, suffi- 

 ciently illustrates its general distribution over this area. From the 

 data supplied by Grisebach, Millspaugh, Harshberger, etc., it is 

 apparent that all the larger islands and most of the smaller ones 

 possess this species. Excluding the small sand-keys, a few hundred 

 yards across, I would imagine that this plant has established itself 

 on every small island where there are beaches. Numbers of beaches 

 were visited by me on the north, south, and west coasts of Jamaica, 

 and the species was noticed on nearly all of them. However, certain 

 restricting influences seem in places to affect its distribution. Thus, 

 Mr. Lansing found it on only four of the nineteen Florida sand-keys 

 examined by him, which contrasts with the prevalence there of 

 such beach plants as Cakile fusiformis, Euphorbia buxifolia, and 

 Suriana maritima that occur on most or on nearly all of them. 



In the West Indies this plant did not present itself to me far away 

 from the beach, as it did in the dry inland plains of Vanua Levu, 

 in Fiji, where it attained a maximum height of 1300 feet above the 

 sea. The other botanists, whose works are at my disposal, say nothing 

 of its inland extension in this region. In the Turks Islands it usually 

 grows over the sandy and rocky surfaces of the smaller cays, which 

 are often only one or two hundred yards across and display sea- 

 drift thrown up by the breakers in the centre. In Gibb Cay, however, 

 which is of greater height, the plants had climbed the sandy slopes 

 to an elevation of nearly fifty feet. On the larger cays they thrive 

 on the dunes behind the beach; but although the conditions in the 

 interior of the islands seem very favourable for their inland exten- 

 sion, I possess no record of their occurrence far from the beach. 



As in other parts of the tropics, the seeds are often to be found in 

 stranded beach-drift; and there can be no doubt that the currents 

 are effective agents in dispersing the buoyant seeds over these 

 seas, since a good proportion can float unharmed for six months and 

 more. They came under my notice on the beaches of Jamaica, 



