Summary of the Chapter
(1) Man in his distribution over the Pacific islands reproduces, but in a less degree, nearly all the difficulties presented by the plant in its dispersal. In both we have the age of general dispersion followed by a suspension more or less complete of the migrating movements; and in both we have differentiation associated with the isolation.
(2) The Pacific islanders possess two sets of food-plants. In addition to those commonly cultivated in our own time, such as the yam, the taro, the banana, &c., there are a number of food-plants now growing wild, but rarely cultivated, and only used when the others fail. These plants, which include the wild yams, the mountain bananas, Tacca pinnatifida, Pandanus odoratissimus, and several others, are regarded as older than the Polynesians in the Pacific, and as having probably formed the food of a pre-Polynesian race that practised only a rude sort of cultivation.
(3) The weeds of Polynesia also fall into two groups. In the first place there are the aboriginal weeds, of which those found in this region by Captain Cook’s botanists in the latter part of the 18th century are taken as examples. These include species of Urena and Sida, besides Waltheria americana, Oxalis corniculata, Bidens pilosa, and many other weeds. In the second place, there are the numerous weeds that are known to have been introduced by the white man since the voyages of the English and French navigators of Captain Cook’s time.
(4) There is reason to believe that many weeds now cosmopolitan in the tropics had obtained their present distribution in America and in the Old World before the Polynesians entered the Pacific. It is thus that we can explain how there existed in these islands at the time of their discovery by Cook, Bougainville, and other navigators of that period, a number of weeds that have their homes in America.
(5) It is not considered that the distribution of aboriginal weeds can materially aid the ethnologist in his study of the early history of man, since birds are regarded as the chief distributors of their seeds and fruits. Whilst man has prepared the conditions for the growth of weeds, the bird has usually brought the seeds.
(6) Amongst interesting plants concerned with man in the Pacific are Aleurites moluccana and Inocarpus edulis, which are regarded as in the main distributed through man’s agency. Gyrocarpus Jacquini is viewed as a tree originally widely dispersed by the currents in the Pacific, but now becoming extinct.
CHAPTER XXIX
BEACH AND RIVER DRIFT
In the south of England.—On the coast of Scandinavia.—In the Mediterranean.—Southern Chile.—Very little effective dispersal by currents in temperate latitudes.—Cakile maritima.—In tropical regions.—River drift.—River and beach drift of Fiji.—Musa Ensete.—The coco-nut.—River and beach drift of Hawaii.—Comparison of the beach drift of the Old and New Worlds.—Summary.