Page:Popular Science Monthly Volume 17.djvu/381

Rh lichens, and ferns. The spores of fungi are so minute as to require a microscope to see them, and so numerous that Fries says he counted in a single specimen of Reticularia maxima no less than 10,000,000. What wonder, then, that with seeds so minute and so numerous these plants should be almost universally distributed? Out of 200 lichens, for instance, brought home to England by the Antarctic Expedition under Sir James Ross, almost every one has been ascertained to be also an inhabitant of the northern hemisphere, and most of them of Europe. It is easy enough to imagine the wind capable of transporting minute spores to immense distances over land and ocean. Many plants not possessing small seeds are carried off bodily by the wind to distant localities. Of these there is the "leap-in-the-field," or the "wind-witch," inhabiting the steppes of southern Russia. "A poor thistle-plant," says Schleiden, "it divides its strength in the formation of numerous dry slender shoots, which spread out on all sides, and are entangled with one another. . . . The domes which it forms upon the turf are often three feet high and sometimes ten to fifteen in circumference, arched over with naked, delicate, thin branches. In the autumn the stem of the plant rots off, and the globe of branches dries up into a ball light as a feather, which is then driven through the air by the autumnal winds over the steppe. Numbers of such balls often fly at once over the plain with such rapidity that no horseman can catch them; now hopping with short, quick springs along the ground, now whirling in great circles round each other, rolling onward in a spirit-like dance over the turf, now caught by an eddy, rising suddenly a hundred feet in the air; often one 'wind-witch' hooks on to another, twenty more join company, and the whole gigantic yet airy mass rolls away before the piping east wind."

Still another plant, the so-called "rose of Jericho," but really one of the Cruciferæ, has a similar method of dissemination. Professor Lindley says of it: "At the end of its life, and in consequence of drought, its texture becomes almost woody, its branches curve up into a sort of ball, the valves of its pods are closed, and the plant holds to the soil by nothing but a root without fibers. In this state the wind, always so powerful on plains of sand, tears up the dry ball and rolls it upon the desert. If in the course of its violent transmission the ball is thrown upon a pool of water, the humidity is promptly absorbed by the woody tissue, the branches unfold, and the seed-vessels open; the seeds, which, if they had been dropped upon the dry sand, would never have germinated, sow themselves naturally in the moist soil where they are sure to be developed, and the young plants will be certain of nourishment. Specimens of this curious production are sometimes brought from Palestine, and, although they may be many years old, will, if placed in water, start, as it were, from their slumbers, and assume all the appearance of plants suddenly raised from the dead." The