MISCELLANEOUS PLANTS 



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species of Tournefortia are of themselves able to cross the broadest 

 ocean. 



Whilst my first sea-water flotation experiments, carried out on 

 Keeling Atoll and in the Turks Islands, were limited in duration, 

 they established the great buoyancy of the fruits of both species of 

 Tournefortia, none of them sinking during a period of forty days in 

 the case of T. argentea and of sixty days in that of T. gnaphalodes . 

 In a subsequent experiment made in England four fruits of T. argentea 

 that had been gathered twenty-one months were placed in sea- 

 water, all of them floating and displaying sound seeds after a year's 

 immersion. In the same way I made a later experiment in England 

 on fruits of T. gnaphalodes collected twelve months before. All 

 remained afloat and retained sound seeds after six months in sea- 

 water. They were sown out, and after a couple of months several 

 germinated and produced healthy seedlings. The delay in the 

 subsequent germination conveys a warning against expecting quick 

 results when testing the germinative capacity of seeds after prolonged 

 flotation in sea- water. There was also delay in the case of the fruits 

 of T. argentea which had been forty days afloat in sea-water on 

 Keeling Atoll. Dr. Treub, Director of the Botanic Gardens of 

 Buitenzorg, Java, sowed seven of them in one of his houses, and 

 all germinated in the course of two months ( Journ. Vict. Inst. Lond. 

 1889). 



However, the dispersal of the fruits of Tournefortia by currents 

 is not always so simple as it appears to be. In the case of T. gnapha- 

 lodes it was necessary to employ a good number of fruits in my 

 experiments, since about half of them had no seeds, the contracted 

 seed-cavities indicating their early failure. Another influence that 

 goes towards reducing the number of fruits effective for dispersal 

 is the tendency of the fallen fruits of this plant to germinate unsuc- 

 cessfully on the sand beneath the shrub, a matter already mentioned. 

 It is thus likely that a large number of the fruits swept off a beach 

 by the waves and carried off by the currents may be ineffective for 

 purposes of dispersal. 



With reference to the distribution of Tournefortia gnaphalodes 

 in the ten islands of the Turks Group, it may be said that the plant 

 came under my notice on all of them except Cotton Cay; but it is 

 highly probable that it occurs on that island also, as my examination 

 of it was incomplete. In the two largest islands of Grand Turk and 

 Salt Cay it grows in quantity, both on the edge of the beaches and 

 on the sandy belts in the rear. On Grand Turk it grows around the 

 greater portion of the island, and is especially abundant along the 

 length of the weather or east side. But it thrives almost as well 

 on the rocky surfaces of small cays, such as Penniston, Long, and 

 Pear Cays, where sandy beaches are either scanty or absent. Whilst 

 it grows over the surface of such small rocky cays, which are from fifty 

 to a hundred yards in width and from twenty-five to thirty-five feet 

 in height, it rarely strays far from the vicinity of the beach in the 

 larger islands, and does not usually climb far up their slopes. How- 

 ever, it grows on the sandy top of Round Cay, which, though forty- 

 five feet in height, is the smallest of the islands. In islands, like 



