xxv GARDENIA 313 



valves being scattered around. If one of the fruits gathered from 

 the plant is kept soaking in water for some time it will begin 

 to dehisce ; and this is probably what occurs with fallen fruits 

 in wet weather. Dr. Hillebrand regards the fruits of the Hawaiian 

 species as indehiscent. I did not myself examine them, but it 

 is not improbable that, like those in Fiji, they dehisce whilst lying 

 soaking on the ground. 



Judged merely from the dispersal standpoint, the fruits of the 

 Fijian Gardenias come near to those of Pittosporum, and both can 

 be in a sense described as baccate capsules. The flat, crustaceous 

 seeds of Gardenia, which are usually two or three millimetres in 

 size, are also well fitted for passing without injury through the 

 digestive canal of a bird. It is likely that the two genera have 

 been dispersed in the Pacific by the same kind of birds ; and 

 it should be remarked that their distribution is somewhat similar, 

 both belonging to the warm regions of the Old World. 



It might at first appear from some experiments of mine made 

 in Fiji that the dried fruits of Gardenia could be dispersed over 

 oceans by the currents. This receives some support by the 

 preference for a littoral station sometimes shown by G. tahitensis 

 in Tahiti, and by the occurrence of G. zanguebarica in the East 

 African strand-flora (Schimper's Ind. Mai. Strand-flora^ p. 131). 

 It will, however, be pointed out that currents could only have 

 aided the dispersal of the genus to a limited extent. The fresh 

 fruits of Fijian species, with or without the adherent calyx, have 

 little or no buoyancy, and the seeds sink even after drying for 

 months. But it was ascertained that fruits which had been kept 

 for three months floated after four or five weeks' immersion in sea- 

 water. On examination, however, it was found that the valves 

 gaped a little, being only held in apposition by the adherent calyx, 

 and that water had penetrated into the interior, the pulp being in 

 a state of decay. The fruits were, in fact, kept afloat in the latter 

 part of the experiment partly by the investing calyx and partly 

 by gas generated in the decomposing pulp. Ultimately they broke 

 down altogether and the seeds sank. In the " rough-and-tumble " 

 of ocean-transport this could scarcely be deemed an effective means 

 of dispersal ; and in the open sea a fortnight would probably 

 represent the limit of the floating power. It is to the agency that 

 has distributed the genus Pittosporum over the Pacific that we 

 must look for the explanation of the dispersal of Gardenia over the 

 same ocean, namely, to birds. 



