218 PLANTS, SEEDS, AND CURRENTS 



and Pacific Oceans might do a great deal more. Though, as is 

 observed below, it is tenacious of locality, there are evidently some 

 deterrent influences which restrict its dispersal, influences, however, 

 that are not concerned with unfitness for dispersal by currents, since 

 my experiments show that in their ability to float unharmed for 

 many months in the sea its seeds are not inferior to those of Ipomcea 

 pes-caprce, one of the most typical beach plants of the tropics. 



Let us look at some of the features of its distribution. In North 

 America, according to the data supplied by Harshberger, it grows 

 on the shores of the Mississippi delta, on the Louisiana beaches in 

 association with Ipomosa pes-caprce, and around the coast lagoons 

 near La Paz in Lower California. In the West Indies, as we learn 

 from Grisebach, Hart, Millspaugh, and others, it grows on the 

 beaches of Jamaica, the Cayman Islands, Porto Rico, and Trinidad ; 

 and it has long been known from the Guianas and Brazil. It is also 

 a Mediterranean plant, and it has been found also in the Azores 

 as well as in the Hawaiian Islands in the centre of the Pacific. 



Until recently it was only known from one locality in the Azores, 

 namely, Porto Pym in Fayal, where it was observed by Watson in 

 1842, by Brown in 1894, and by myself in 1913 and 1914. However, 

 during my stay on Pico I found it thriving on a beach just south 

 of Magdalena at the western end of the island. In Hillebrand's 

 Flora of the Hawaiian Islands it is only recorded from Niihau, an 

 island at the extreme north-west of the group, where it was collected 

 by Remy half a century or more ago. 



Its behaviour in the Cayman Islands is characteristic. Mr. Savage 

 English in his account of Grand Cayman (Kew Bulletin, No. 10, 1913) 

 refers to a small colony which had established itself on the shore 

 in one locality, presumably after the hurricane of 1903, adding that 

 it was new to the islanders. However, Dr. Millspaugh, who visited 

 the Cayman Islands in February 1899, found it on the beach at Spot 

 Bay in Grand Cayman, as well as on Cayman Brae (Plant. TJtow., L, 

 85). The plant is evidently tenacious of locality, since it still grows 

 in the Azores in the same locality where it was first noticed more 

 than seventy years ago. Unlike its companion beach plant, Ipomcea 

 pes-caprce, its stem is mostly buried in the sand, only the leaved 

 and flowering shoots usually showing, a feature described in detail 

 by Dr. Millspaugh. When I visited Porto Pym on March 12, 1913, 

 only a few young leaf-shoots were showing above the sand. A month 

 later they were much more numerous. On July 21, 1914, it was 

 flowering abundantly and in early fruit; whilst numbers of the 

 previous year's seeds bared of their hairy covering lay on the sand. 

 On August 12 many of the capsules had matured and were opening, 

 displaying their hairy seeds. 



To test their buoyancy, a number of the hairy seeds of the same 

 year and of the bared seeds of the previous year were put in sea- water 

 a few weeks after collection. After three months 20 per cent, of 

 the hairy seeds and all of the bared seeds remained afloat, and 

 after seventeen months 10 per cent, of the hairy seeds and 90 per 

 cent, of the bared seeds were still floating. The survivors germinated 

 freely, and from them I raised plants. If the currents are responsible 



