WEST INDIAN AND WEST AFRICAN FLORAS 85 



The question is put and answered in the table given on p. 86, in the 

 columns of which are embodied the results of the author's observa- 

 tions and experiments, as well as literary research, extending over 

 a period of more than thirty years, and carried out in many localities 

 both in the Old and the New World. There are not more than three 

 or four of the fifty-three plants named in the table with which he is 

 not familiar in their homes, and in all but one he is acquainted 

 with their fruits and seeds, and has investigated their capacity for 

 dispersal by currents. 



With the exception of the group of small-seeded plants, which, 

 since they raise other considerations besides those concerned with 

 currents, are not here dealt with and are discussed in Note 21 of the 

 Appendix, we have represented in this table the principal littoral, 

 estuarine, and riverside plants of the West Indies. All offer them- 

 selves for the application of the test. 



Explanatory Notes of the Following Table 



(a) The results given in the buoyancy column refer only to the 

 period during which the seed retains its germinative capacity 

 whilst afloat. Flotation may continue long after the death of the 

 seed. 



(b) The plants marked ? in the West African column occur in 

 all probability in West Africa, though in the works of reference at 

 my disposal that region is not specially particularised, and they 

 are as a rule merely described as found on all tropical coasts. It 

 may be assumed that plants like Suriana maritima and Colubrina 

 asiatica, which are found in the West Indies and in East Africa, 

 also occur in West Africa, though in the case of the Old World 

 they are usually only mentioned as existing on all tropical 

 coasts. 



(c) The occurrence of the plants on the Pacific coasts of tropical 

 America is indicated in the table as far as the data at my disposal 

 allow. The distribution is often stated in such a general way in 

 works of reference that it is not possible to learn with certainty 

 whether or not the plant concerned exists on the Pacific as well as 

 on the West Indian side of the New World. This is unfortunate, 

 since the question is one of considerable interest, especially as regards 

 true littoral plants. It is, however, probable in most of the cases 

 where no indication is given in the table that the plant also grows 

 on the Pacific coast. 



(d) The list of beach plants restricted to the New World could be 

 considerably extended if buoyancy data were available; but it is 

 very doubtful whether any of them would possess seeds or fruits 

 with great floating powers. One may mention Ernodea litoralis, 

 Rhachicallis rupestris, and Phyllanthus falcatus. Then there are 

 plants of Amarantaceous genera, such as Alternanthera and Litho- 

 phila, as well as different sedges, such as Cyperus brunneus, etc., 

 and grasses, such as Uniola paniculata, Cenchrus tribuloides, etc. 



