56 A NATURALIST IN THE PACIFIC CHAP. 



character of the fruits of the " absentee " trees, which a traveller 

 fresh from a visit to the coral islands and reef-girt coasts of the 

 South Pacific sadly misses on the Hawaiian beaches. We notice 

 in the first place that the absent trees, such as Barringtonia 

 speciosa, Cerbera Odollam, Guettarda speciosa, Heritiera littoralis, 

 Terminalia Katappa, &c., have large fruits which could only have 

 been carried to Hawaii by the currents, the agency of birds being 

 quite out of the question. On the other hand, almost all the 

 littoral plants of Hawaii, whether trees, shrubs, or herbs, which 

 are regarded as truly indigenous by Mann, Hillebrand, and other 

 Hawaiian botanists, have only small fruits or seeds available for 

 dispersal, from which the agency of birds cannot, on the point or 

 size, be excluded. Amongst these shore plants possessing buoyant 

 seeds or fruits are Cassytha filiformis, Colubrina asiatica, Ipomea 

 pes caprae, Scaevola Kcenigii, Vigna lutea, and Vitex trifolia; whilst 

 amongst the plants with non-buoyant fruits or seeds are to be 

 reckoned Heliotropium anomalum, H. curassavicum, Tephrosia 

 piscatoria, Tribulus cistoides, &c. The seeds or seedvessels of the 

 plants of the buoyant group possess great floating powers ; and it 

 seems at first sight scarcely credible that the currents which have 

 failed to establish Barringtonia speciosa, Guettarda speciosa, and 

 the other trees that through this agency have often found a home 

 on the remotest islands of the Pacific, should have succeeded in 

 the instances of plants like Scaevola Kcenigii and Vitex trifolia. 



It would indeed almost seem that in nearly all cases where it 

 would be impossible in point of size for a bird to transport the 

 fruit or seed of a shore-plant to Hawaii, such a plant is not to be 

 found in the strand-flora of that group, even though it is well 

 adapted for dispersal by the currents. Many of the littoral trees 

 missing from the Hawaiian coast-flora, having large buoyant 

 fruits, come into this category ; and grave suspicion is thus 

 apparently cast on the agency of the currents in the case of the 

 plants with small fruits and seeds that really compose the strand- 

 flora, even when their capacity for sea- transport has been well 

 established by observation and experiment. The efficacy of the 

 currents would thus seem to be called into question for the whole 

 littoral flora of Hawaii. 



If, however, we were to adopt such a sweeping conclusion we 

 should be led into an error. It is pointed out in the following 

 chapter that nearly all these large-fruited beach trees that are 

 found far and wide over the South Pacific, but are absent from 

 Hawaii, do not occur as indigenous plants in America. If, there- 



