The progeny of the Willow is provided with long projecting hairs which curl together to form a tiny balloon. Feathery attachments called pappus enable the children of the Dandelion, the Thistle and the Fire Weed to go on long jaunts of exploration. The seed-pods of the Sycamore are great rollers. Even ordinary nuts and fruits may be blown to considerable distances by the strong winds of autumn. The many edible seeds and fruits are carried gratis by birds and animals. The Mistletoe, for instance, is distributed entirely by them. Walnuts, Butternuts, and Acorns bear water travel well, as do certain of the hard seeds. The Arrowhead (_Sagittaria_) has a self-made water-wing on which its offspring float. Plant seeds, which like to travel on animals, all provide themselves with grappling irons in the shape of sharp hooks, spurs and spines with which they cling to their carriers. Everybody in the northern United States knows of the avidity with which the Cockle-bur clings to any passing object. The Touch-me-not (_Impatiens_), the Wistaria, and a host of others, actually shoot their seeds from their pods as from a gun. Every vagrant breeze, every purling brook, every deep river, every ocean current, is a highway of travel in plantdom. The birds, the beasts, the insects, and not least, man himself, are involuntary vehicles on which our vegetable friends tour the world. The spores of Mosses, Lichens, Fungi and other cryptogams are so light that they find no difficulty in mounting into the air and traveling across the Atlantic or Pacific Oceans at will. The complete record of plant conquests would fill many volumes. Their operations have extended into every land and have had influence on the world’s history. It very often happens that plant invaders become so quickly and thoroughly naturalized in a strange country that they go a long way toward supplanting the original inhabitants in a very short time. It was Darwin who first noticed the extensive conquests of the Cardoon Artichoke (_Cynara Cardunculus_) in South America. In one section, these prickly plants covered an area of several hundred square miles, having entirely superceded the aborigines. It is well known that the most troublesome of the American weeds are of British origin. On the other hand, the American water weed _Anacharis_ blocks up small English streams. The grass called _Stipa Tortilis_ has captured the steppes of southern Russia. The love of change seems to be an inherent tendency in plantdom. The Pigweed and the Morning Glory have come north from the tropics. The Canada Thistle, originally a foreigner in North America, has spread all over Canada and New England. The American _Erigeron Canadense_ has emigrated to all parts of the world. The flora of Scandinavia, like its people, are aggressive colonizers. More than one hundred and fifty species have reached New Zealand alone and nearly as many have established themselves in the eastern United States.