xxvi PLECTRONIA 355 



Mangaia, and Rarotonga. The remarkable distribution of the 

 Pacific plant at once attracts attention. I was very familiar with 

 it in Hawaii, where it forms one of the commonest bushes in open- 

 wooded and thinly vegetated districts at elevations usually ranging 

 from the coast to 3,000 feet. Its small, white, somewhat fleshy 

 fruits would attract birds, and the hard pyrenes would be able to 

 pass unharmed through a bird's digestive canal. It seems probable 

 that, like Rhus semialata, this plant entered the Pacific Ocean from 

 the north-west, taking the route by Japan and the Bonin Islands, 

 and following the trend of the archipelagoes over Polynesia (see 

 Bot. ChalL Exped., Introd. p. 18; Journ. Linn. Soc. Bot., vol. 28, 

 1891, &c.). 



VlSCUM (Loranthaceae). A single species, V. articulatum, 

 which has its home in Southern Asia, is found in most of the 

 Pacific groups, such as Hawaii, Marquesas, Tahiti, Rarotonga, Fiji, 

 &c. The dispersal of the genus by frugivorous birds is well known. 



PLECTRONIA (Rubiaceae). I have found it more convenient to 

 place this genus here, although there are probably one or two 

 species peculiar to Fiji. This genus of shrubs, which is spread 

 over the warm regions of the Old World, is represented by two 

 widely distributed species in Polynesia, Plectronia odorata (B. and 

 H.) and P. barbata (B. and H.), the first alone extending to Hawaii. 

 I was very familiar with P. odorata in Hawaii and was much in- 

 terested in its mode of dispersal, since the species has also been 

 found in Fiji, Tahiti, the Marquesas, and Pitcairn Island (Maiden). 

 In one locality, where an old lava-field was partially covered by its 

 bushes then in fruit, the doves were feeding greedily on the drupes, 

 the " stones " of which, as well as the partially digested fruits, were 

 to be seen in quantity in their excrement near a water-hole. The 

 stones are very hard and about a third of an inch (8 mm.) in length, 

 and are exceedingly well suited for transport by frugivorous 

 birds. It was very probably to one of these species of Plectronia 

 that Peale alluded when he wrote of the berries of a species of 

 Canthium forming the principal food, on one of the Paumotu 

 Islands, of Numenius tahitensis, a curlew that has its home in 

 Alaska, migrating south in autumn to Hawaii, Tahiti, and the 

 Paumotu Group (Wilson's Aves Hawaiienses). 



BOERHAAVIA (Nyctagineae). Two or three Asiatic species or 

 this genus, B. diffusa, B. tetranda, &c., are spread all over the 

 Pacific islands from the Fijis to the Paumotus and northward to 

 Hawaii. Similar or allied species occur on the coral islands of the 

 Indian Ocean, as on Diego Garcia and on Keeling Atoll. Though 



A A 2 



