ravels fast, for it travels like Ariel. In
much the same way, the coltsfoot grows on all new English railway
banks, because its winged seeds are wafted everywhere in myriads on the
winds of March. All the willows and poplars have also winged seeds: so
have the whole vast tribe of hawkweeds, groundsels, ragworts, thistles,
fleabanes, cat's-ears, dandelions, and lettuces. Indeed, one may say
roughly, there are very few plants of any size or importance in the
economy of nature which don't deliberately provide, in one way or
another, for the dispersal and dissemination of their fruits or
seedlings.

Why is this? Why isn't the plant content just to let its grains or
berries drop quietly on to the soil beneath, and there shift for
themselves as best they may on their own resources?

The answer is a more profound one than you would at first imagine.
Plants discovered the grand principle of the rotation of crops long
before man did. The farmer now knows that if he sows wheat or turnips
too many years running on the same plot, he 'exhausts the soil,' as we
say--deprives it of certain special mineral or animal constituents
needful for that particular crop, and makes the growth of the plant,
therefore, feeble or even impossible. To avoid this misfortune, he lets
the land lie fallow, or varies his crops from year to year according to
a regular and deliberate cycle. Well, natural selection forced the same
discovery upon the plants themselves long before the farmer had dreamed
of its existence. For plants, being, in the strictest sense, 'rooted to
the spot,' absolutely require that all their needs should be supplied
quite locally. Hence, from the very beginning, those plants which
scattered their seeds widest throve the best; while those which merely
dropped them on the ground under their own shadow, and on soil
exhausted by their own previous demands upon it, fared ill in the
struggle for life against their more discursive competitors. The result
has been that in the long run few species have survived, except those
which in one way or another arranged beforehand for the dispersal of
their seeds and fruits over fresh and unoccupied areas of plain or
hillside.

I don't, of course, by any means intend to assert that seeds always do
it by the simple device of wings or feathery projections. Every variety
of plan or dodge or expedient has been adopted in turn to secure the
self-same end; and provided only it succeeds in securing it, an