round the world. The shepherd's-purse, with others, is common in China, on the most eastern coast of Asia. One kind of mallows belongs to the East Indies; another to the coast of the Mediterranean. The gimson weed, or Datura, is an Abyssinian plant, and the Nicandra came from Peru. It is supposed that the amaranths or greenweeds, so very common here, have also been introduced, though possibly only from the more southern parts of our own country.
Some few American plants have been also carried to Europe, where they have become naturalized; but the number is very small. The evening primrose, and the silkweed, among others, have sowed themselves in some parts of the Old World, transported, no doubt, with the tobacco, and maize, and potato, which are now so widely diffused over the Eastern continent, to the very heart of Asia. But even at home, on our own soil, the amount of native weeds is small when compared with the throngs brought from the Old World. The wild cucumber, a very troublesome plant, the great white convolvolus, the dodder, the field sorrel, the pokeweed, the silkweed, with one or two plantains and thistles, of the rarer kinds, are among the most important of those whose origin is clearly settled as belonging to this continent. It is also singular that among those tribes which are of a divided nature, some being natives, others introduced, the last are generally the most numerous; for instance, the native chickweeds, and plantains, and thistles, are less common here than the European varieties.
There are other naturalized plants frequent in neglected spots, about farm-houses, and along road-sides, which have already become so common as to be weeds; the simples and medicinal herbs,
