MISCELLANEOUS PLANTS 



213 



flora that once held the region, now occupied by the Caribbean Sea, 

 which united the Greater Antilles with Central and South America 

 (vide Harshberger, p. 307). From the data given below with respect 

 to the fruits of Grias cauliflora, it would seem that the genus is quite 

 unsuited for dispersal by marine currents. 



The fruits readily get into the floating drift of rivers, on the banks 

 of which the tree so often finds its station. They are elliptical, 

 3 to 3 J inches long, possess eight prominent ribs, and contain a fleshy 

 though tough seed, 1J to 2 inches in length, which is merely, as in 

 Barringtonia, a gigantic hypocotyl, the cotyledons being absent or 

 inconspicuous. The buoyancy of the fruit is entirely due to the 

 husky fibro-ligneous pericarp and to its air-bearing tissue, the seed 

 sinking in water. But though the fruit can evidently float for 

 months, it is far from impervious to water. It soon loses in the 

 floating river-drift the outer thin skin of the living fruit, and water 

 enters freely into the seed-cavity, the membranes investing the seed 

 affording little or no protection. As a result, the floating fruits 

 soon begin to germinate in river-drift. Thus, in one of my ascents 

 of the Black River in January, I estimated that 50 per cent, of the 

 floating fruits were germinating, showing roots up to three inches in 

 length. Forty per cent, had been so long in the water that the seed 

 had disappeared through decay or was in a decaying condition, and 

 there can be little doubt that most of these had originally germinated. 

 Ten per cent, had more or less fresh seeds that had not yet begun to 

 sprout. When the floating fruit reaches the coast, the sea-water 

 kills the seed, whether or not in the germinating state. 



Although when stranded on a sea-coast these buoyant fruits would 

 either be empty or would carry a dead or decaying seed, it cannot 

 be doubted that if the trees were at all frequent on the large island 

 of Hispaniola, about 100 miles away, their fruits would be washed 

 up on the beaches of the Turks Islands. Their absence from the 

 drift of these islands indicates the absence or rarity of the tree on 

 Hispaniola, as well as on Porto Rico and in the neighbouring Lesser 

 Antilles, islands which collectively represent the main source of the 

 foreign beach-drift of the Turks Islands. This implication goes to 

 support the view that Grias cauliflora occupies a very restricted area 

 in the West Indies, an area which it has been unable to extend 

 through the agency of the currents. The species would thus appear 

 to be on the road to extinction in the West Indian region. 



Yet the fruits, useless as they are for the purposes of oversea 

 distribution, are frequent on the beaches for several miles east and 

 west of the Black River estuary in Jamaica. They are also to be 

 found amongst the shore-drift near estuaries on other parts of the 

 coast of this island, wherever the tree thrives at the riverside. 

 Thus, they were noticed near the mouth of the Cabarita River at 

 the south-west corner of the island and near the estuary of the White 

 River on the north side. As they lie on the beaches several still show 

 the protruding rootlets of the germinating seed, but in a shrivelled 

 state. Several also are empty, or display a seed far decayed. 



But when, as not infrequently happens, the seed is still entire, it 

 undergoes a very curious change as it lies within the fruit on the 



