CHAPTER V 



RHIZOPHORA MANGLE AND THE PLANTS OF THE GREAT MORASS OF 

 THE BLACK RIVER DISTRICT IN JAMAICA 



This species of mangrove is so universally spread in the West 

 Indies that there will be no necessity to name the various localities 

 in which I found it. My numerous observations on the plant in 

 Fiji and Ecuador are described at length in my book on Plant 

 Dispersal. Here I will merely add my West Indian observations, 

 contrasting them as occasion requires with the results previously 

 obtained. 



On the Period required for the Growth of Rhizophora 

 Seedlings on the Tree. — Reference will first be made to the length 

 of time that elapses in different species of Rhizophora between 

 fertilisation and the fall of the seedling from the tree. In the work 

 above named (pp. 457, 466) it is stated that whilst Jacquin in the 

 West Indies placed this period at eleven to twelve months for 

 Rh. mangle, my own observations in Fiji for the same species gave a 

 result of eight to nine months. The considerable variation in the 

 length that the seedling attains on the tree will explain this differ- 

 ence. For Rh. mucronata in Fiji, I placed the period at about ten 

 months. These results may now be supplemented by those given 

 by Kerner in his Natural History of Plants (Oliver's translation, 

 I., 603) for another Asiatic species, Rh. conjugata. Apparently 

 quoting Ransonnet, he writes that the hypocotyl reaches its full 

 length of 30 to 50 cm. in from seven to nine months. With these 

 results we have now the requisite data for all the three species that 

 are usually recognised as constituting the genus Rhizophora, and the 

 view expressed in my work that a period of nine or ten months is 

 typical of the genus thus holds good. 



On the Ability of Rhizophora Seedlings to withstand 

 Drying. — It is remarked in my previous work (p. 461) that stranded 

 Rhizophora seedlings would be able to withstand drying for months, 

 provided that they were protected by a covering of vegetable drift 

 or of sand; and an experiment in Fiji is described in which two 

 stranded seedlings, kept dry in my room for nine weeks, developed 

 leaves and roots when afterwards planted in the mud of a mangrove 

 swamp. However, the results of a more recent experiment on 

 West Indian seedlings, which are given below, indicate that under 

 favourable conditions seedlings can retain their vitality in the dry 

 state for five months ; and one cannot doubt that, if the experiment 

 had been conducted under more natural conditions in the tropics, 



96 



