Page:Popular Science Monthly Volume 17.djvu/380

366 Australia. Several species of the mosses (Funaria, Dicranum, and Bryum) are common to the Blue Mountains of Jamaica, the Peak of Teneriffe, and Lapland. Among 133 plants from one of the Pyrenees, Raymond found thirty-five identical with those of Melville Island in the Arctic Ocean. Potentilia anserina grows in North America from Pennsylvania to California and northward, in the northern part of the Old World, in Chili, and in New Zealand; Monotropa uniflora from Canada to Louisiana, in Oregon, in New Granada (South America), and Himalaya Mountains in India; Dichondora repens from Virginia to Chili, in New Zealand, in Tasmania, to eastern Africa, and at the Cape of Good Hope; Adiantum pedatum is found in the eastern United States and Canada, to Oregon, in Kamtchatka, Japan, and Nepaul in India; Crantzia lineata in the United States from Massachusetts to Texas, in South America from Buenos Ayres to Falkland Islands, and in New Zealand; Phleum alpinum inhabits the United States, Switzerland, and the Straits of Magellan.

These few cases will suffice to show the strange and apparently capricious distribution of plants. All these are, of course, supposed to be indigenous to the various countries given as their habitats. Now, according to the theory of natural selection and of descent with modification, we must suppose that all plants have descended from parents like themselves, and have not been specially created where they are now found. When we find, therefore, two plants of the same species, or of the same genus closely allied to each other, inhabiting the United States and Europe, or Europe and New Zealand, we must naturally suppose that at some time or other they had descended from the same kind of an ancestor, but that owing to circumstances they have become widely separated. Plants are not like animals, endowed with locomotive organs, and they must therefore have depended on the elements to transport them. To try and discover these modes of transport, then, we shall now proceed.

The winds undoubtedly exercise an immense influence on the distribution of plants. Many seeds are furnished with a pappus or feathery appendage, by means of which they are easily carried along by the wind. Many of these belong to the Compositæ, such as the dandelion, the thistles, hieraciums, etc. Others are provided with wings, as in the ash and the maple; still others with cottony or feathery tails, as in the anemones and clematis. Again, many are so minute as to be visible to the eye only in the form of smoke, and are so numerous as to be almost uncountable. This is especially the case with fungi, mosses,