The agency of man in introducing these interesting Fan-Palms into the Hawaiian Islands seems out of the question, since they are home productions in a specific sense and are doubtless ancient components of the flora; and, of course, grave objections exist on ethnological grounds, if this genus had originally its home in America. With reference, however, to Pritchardia pacifica of the South Pacific, it is not unlikely that man has aided in the distribution of a palm mainly preserved by planting in and about the villages and set apart from time immemorial for the use of the chiefs.
In this connection the aboriginal names are of some importance and may be very briefly here referred to. The Fijian “Viu,” the “Piu” of Samoa, Tonga, and Futuna, and the Tongan “Biu” are forms of the same name applied to this palm all over West Polynesia; and I have shown in my paper on Polynesian Plant-Names that in the form of “Firo” in the Solomon Islands (Bougainville Straits) and of “Wiru” in Sundanese, one of the Malayan languages, the same name is given to another genus of Fan Palms, namely, Licuala. But since these West Polynesian names do not always conform with the laws of consonantal interchange in this region, they cannot all be considered as indigenous in the languages concerned. If, for instance, “Viu” is an indigenous Fijian name, as no doubt it is, since it follows the phonetic laws affecting the Malayan and Fijian languages, “Piu” must be a foreign word in Samoa and Tonga, and “Biu” must be another introduced Tongan name.... The Fijians have in “Sakiki” (contracted into “Saii” in the Somosomo dialect) another name for this palm. This is probably derived from “Kiekie,” a mat-word in different forms in various Polynesian groups, and applied in many islands to the plants that supply the materials for mat-making, such as Pandanus and Freycinetia.
The Hawaiian generic name of “Loulu” for these palms appears to be quite local; but it may possibly have a common origin with “Roro,” one of the Fijian names of Cycas circinalis. It is pointed out by Hillebrand that the Hawaiian name of the edible kernels of these palms, “Hawane” or “Wahane,” occurs in the Marquesas as “Vahana” applied to the palm, a comparison that is on linguistic grounds quite legitimate. “Vaake” is another Marquesan name, which recalls “Vakoa,” the Malagasy word for Pandanus.
When we compare the variety of the names of the Pritchardia fan-palms in the Pacific Islands with the prevailing uniformity of the names of cultivated plants transported by the aborigines in their migrations from Malaya, such as the taro, the yam, the sugar-cane, the coco-nut, and the Malay-apple, we perceive that the testimony of the names points to the same conclusion as the botanical evidence, namely, that the ancestors of the Hawaiians found these palms in the group at the time of its occupation. In the South Pacific much uncertainty prevails. The ancestors of the West Polynesian peoples evidently brought the word for a fan-palm from their Malayan home; but it is doubtful if they found Pritchardia already established in all the islands; and the apparent home of the genus in America prevents us from attributing to a palm, that is by some botanists regarded as confined to the Western Pacific, a home in the neighbouring regions to the west. There is thus a lack of agreement between the botanical and ethnological indications as regards the original American origin of Pritchardia in the South Pacific.
There remain then the agencies of the currents and of birds. A singular feature in the distribution of the Hawaiian species, Pritchardia gaudichaudii, at once affords a clue as concerning the dispersal in the North Pacific. Dr. Hillebrand remarks that this palm covers part of Bird Island, a small volcanic rock forming an outlier of the Hawaiian group about 400 miles north-east of Kauai. Here the agency of birds is suggested, since it is scarcely likely, though, as shown below, not impossible, that stranded fruits of the palm could have established themselves in this fashion. Mr. Perkins has an interesting note on the food of Ciridops anna, an Hawaiian bird, now nearly extinct, that feeds principally on the blossoms and unripe fruits of the Loulu palms, probably of this species. The drupes when fresh have a somewhat fleshy mesocarp and are about 9⁄10 of an inch (22 mm.) across, and their crustaceous inner shell would undoubtedly fit the seeds for dispersal by frugivorous birds like pigeons. The fruits of the other two Hawaiian species are considerably larger, that of P. macrocarpa being, according to Linden, of the size of a nut of Juglans regia, that is, about 11⁄8 inch or 29 mm., whilst that of P. martii, as we learn from Hillebrand, is from 11⁄2 to 2 inches or 37 to 50 mm. Allowing for the variation in size of the fruits within the limits of the genus, there need be no more difficulty in assuming that the original species had fruits that could have been brought by birds, than in holding that the fruits of Elæocarpus have been carried to Hawaii in the same fashion. The drupes of Pritchardia pacifica are barely half an inch in diameter. They are fitted by reason of their hard crustaceous endocarp for dispersal by fruit-pigeons; and I may here add that these birds are known to distribute the fruits of other palms, such as Kentia and Areca, in the islands of the South Pacific (Bot. Chall. Exped. iv. 308, 312).
Both in Hawaii and in Fiji I experimented on the capacity of Pritchardia drupes for dispersal by the currents. Those of the Hawaiian species, P. gaudichaudii, have when well dried a light buoyant rather fibrous mesocarp which enables them to float in the case of a good proportion of the fruits for at least five weeks. I had no opportunity of testing the buoyancy of the fruits of P. martii, another Hawaiian species; but, judging from the existence in the coats of a fibrous layer as described by Hillebrand, they ought to display some floating power. The fruits of P. pacifica, the South Pacific species, lack the light buoyant covering of the Hawaiian species above referred to, and display little or no floating power even after drying for weeks. Looking at the results of these experiments, it would seem that it is not impossible that Hawaii received the genus through the agency of the currents; but it seems scarcely probable, since it could only have been derived from America, and the American species grows in the interior of the continent and not near the sea-border. The possibility of course exists; but I am inclined to attribute the presence of Pritchardia in Hawaii to bird-agency.
My position from the standpoint of dispersal with regard to Pritchardia in the Pacific is this. The Hawaiian species I would consider as American in origin. The Marquesan species, unless recently described, still awaits detailed investigation. The West Polynesian species of Fiji and Tonga, according to the principles of distribution prevailing in the South Pacific, ought to hail from the west.
Summary.
(1) Whilst the earliest age characterised by the Coniferæ was restricted to the Western Pacific, and whilst the following age of the Compositæ and Lobeliaceæ, mainly American in their affinities, was concerned with the regions of Hawaii and Tahiti, we have now to discuss the Malayan era during which the bulk of the plants were derived from the nearest tropical regions of the Old World. Here we have to deal with the low-level flora of Hawaii, that is to say, with the plants of the levels below 4,000 or 5,000 feet, and with almost the entire floras of the areas of Fiji-Samoa and of East Polynesia. The whole of the tropical Pacific is here concerned, and not a portion of it, as in the two preceding eras; and in our comparison we shall see that there are two, and not as heretofore three, regions to be regarded—the Hawaiian in the North Pacific, and the whole Polynesian area of the South Pacific extending from Fiji to Tahiti.
(2) Here the frugivorous bird has been the principal agent in dispersing the plants, quite two-thirds of the genera possessing drupes or berries that would attract such birds.