Chapter XXVII.)

The large Euphorbiaceous genus Phyllanthus, spread universally over the tropics and containing some 500 known species, clearly indicates by its distribution in the Pacific islands that genera with dry fruits, such as are typical of the order, are as widely distributed and just as much at home in these islands as the genera with fleshy fruits, such as Psychotria and Cyrtandra. The small trees and shrubs of Phyllanthus are common in dry, open, partially wooded districts near the sea-border. The genus attains its greatest development in this ocean in New Caledonia and Fiji; and since the number of species diminishes the further we penetrate the Pacific, it can be scarcely doubted that the genus has entered this ocean from the west. In Fiji there are at least 20 species, of which probably half are not recorded from elsewhere. In Samoa there are seemingly but few peculiar species. In Hawaii there is only one indigenous species, and that is endemic. The genus, however, has developed a lesser centre of distribution in East Polynesia, there being about a dozen species known from Tahiti and the Marquesas, of which half are peculiar to one or other of those groups. From experiments made by me in Fiji on the fruits and seeds of two species it was evident that they possessed little or no capacity for dispersal by the currents. We look, therefore, to the birds, and in this connection it is of interest to note that this genus is included amongst those known to be dispersed by birds in the Pacific, some of the fruits having been found in the crops of fruit-pigeons shot by Prof. Moseley in the Admiralty Islands (_Bot. Chall. Exped._, Introd. 46; iv. 308).

PRITCHARDIA (Palmaceæ).

This genus of Fan Palms supplies an instructive lesson for the student of plant-distribution, more especially with reference to the loss of the endemic reputation of a genus. Regarded by the earlier botanists who visited the Pacific as identical with the familiar Asiatic Talipot Palm (Corypha umbraculifera), the Fan Palms of this region, as represented in Fiji and Hawaii, were subsequently placed by Seemann and Wendland in a new genus restricted to Polynesia and named after a former British Consul in Fiji. Since that time it has lost its reputation as a peculiarly Pacific genus, since a species (Pritchardia filifera) has been found lingering in a few valleys in Arizona, where it enjoys the distinction of being the most northerly in station of all the world’s palms (Linden in _Illustr. Hort._ vol. 24, 1876-77). It would thus appear that the Pacific islands have derived this genus of palms from the western part of North America, but the whole question is beset with many difficulties, and not the least is that connected with the confusion that seems to reign in several cases as regards the allocation and identity of the species.

Six species are named in the _Index Kewensis_, viz.: Pritchardia macrocarpa, restricted to Hawaii; P. martii and P. gaudichaudii, of the Pacific islands; P. pacifica, assigned to Fiji; P. vuylstekeana, from the Paumotus; and P. filifera, from the west side of North America. Though it is sometimes difficult to reconcile this account of the distribution of the genus in the Pacific with views held by other botanists, it offers the safest basis for the future investigation of the subject. It would be, however, necessary to remember that Pritchardia gaudichaudii and P. martii are regarded by Hillebrand as peculiar to the Hawaiian Islands, and that the exact locality of the Paumotu species is not very definitely settled, if it depends on the remarks made on this species in the _Gardeners’ Chronicle_ for 1883. No mention is indeed made by Drake del Castillo of any Tahitian or Paumotuan species.

Whilst in Hawaii and Fiji I was much interested in these palms, and the following remarks are merely intended to be a contribution to the subject. According to Seemann, Hemsley, Drake del Castillo, and Burkill, Pritchardia pacifica, which often attains a height of thirty to thirty-five feet, occurs in Fiji, Tonga, Samoa, and the Marquesas, but it does not exist in Tahiti, and Cheeseman does not include it in the Rarotongan flora. Except in the Tonga Group, where, according to Lister as quoted by Hemsley, the palms form conspicuous objects along the weather shore of the island of Eua, this species is rarely found in the wild state in the South Pacific. This especially applies to Fiji, as Mr. Horne also observes; and at most one is accustomed to see (to employ the words of Dr. Seemann) one or two trees outside a village which are reserved, as in many parts of Polynesia, for the use of the chiefs who employ the leaves for fans and for other purposes. But even this reason for preserving the palms scarcely now exists in Fiji, and at the time of my sojourn in Vanua Levu (1897-99) the trees were rare enough to be regarded as curiosities. In the Marquesas, according to Bennett (quoted by Seemann), they grow in groves in the valleys of the interior. Dr. Reinecke does not even include the species in the Samoan flora, but mentions it with the Date-Palm (Phœnix dactylifera) as if it were recently introduced. It was, however, found in that group by the United States Exploring Expedition about 1840, and this is evidently the palm referred to by Captain Cook as existing at his time in the Tongan Group.

The Hawaiian species of the palm appear to be three in number, Pritchardia gaudichaudii and P. martii, both regarded by Hillebrand as confined to the group, and P. macrocarpa of Linden, also endemic (_Illustr. Hort._ vol. 26). The two first-named species are evidently on the road to extinction in the wild state, and often find their last refuge on rocky, almost inaccessible, inland cliffs. Pritchardia gaudichaudii, about twenty feet in height, is found in the wild state, as we learn from Hillebrand, on the islands of Molokai and Hawaii. It was at one time frequently met with near native dwellings; but during my sojourn in 1896-97 on the last-named island it was not at all frequent, and as a rule only came under my notice occasionally in clumps of three or four trees on the Kona and Puna coasts, as near Kiholo, Milolii, and Kalapana. However, it was more frequent in the Waimanu district of Kohala in the same island. Here I noticed it growing in clumps in precipitous rocky situations at elevations ranging from 1,200 to 2,000 feet. The other palm mentioned by Hillebrand, P. martii, is only five or six feet high, and is confined mostly to Oahu and Molokai.

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 1-1/8 inch or 29 mm., whilst that of P. martii, as we learn from Hillebrand, is from 1-1/2 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.

(3) The genera representative of the first part of this era are those which have only peculiar species in Hawaii, and are composed in the South Pacific either entirely of peculiar species or sometimes of a mixture of endemic and non-endemic species. It is an era of complete isolation in Hawaii and often of a partial connection between the groups of the southern region. Except to some extent in the South Pacific, the dispersing agencies are now no longer active between the groups.

(4) Amongst the genera typical of this period are Pittosporum, Gardenia, Psychotria, Cyrtandra, and Freycinetia.

(5) The two genera of the Rubiaceæ, Psychotria and Coprosma (the last belonging to the mountain-flora), appear to be well suited for the investigation of the effect on distribution of the geographical position of the home of the genus, the first with 600 to 700 species distributed over the tropics of the Old and New Worlds, the second with some sixty species having its home in New Zealand.

(6) From the Pacific Cyrtandras we derive the lessons that the display of great formative power in a genus may not be a peculiarity of an insular flora; that the isolation of an oceanic archipelago does not necessarily induce “endemism,” but merely intensifies it; and that the production of new species within the limits of a genus like Cyrtandra may be nearly as active on the mainland as in an island in mid-ocean.

(7) From the Freycinetias we learn that it may be possible to connect the distribution of a genus of plants with that of a genus or a family of birds. Just as in Chapter XXIV we endeavoured to connect Coprosma and Porphyrio (the Purple Water-Hens), so we here suggest a connection, in their range over the Pacific, between the Freycinetias and the Meliphagidæ (the Honey-eaters), a connection that in the last case at least belongs to the past.

(8) From the genus Phyllanthus we learn that genera with dry fruits may be as widely distributed and may display the same formative power in the Pacific as those with fleshy fruits that would seem much more likely to be dispersed by birds. Here again we obtain an indirect indication that species-making in these islands is not altogether dependent on isolation.

(9) In the case of the genus Sapindus we are apparently compelled to infer that its large seeds (in the present species an inch in size) have been transported by birds to Hawaii. Yet in point of size the difficulties here raised are no greater than those arising from the existence of such genera as Sideroxylon and Elæocarpus in Hawaii, the fruits of which are known to attract frugivorous birds.