Among seeds that trust for their disposal to the wind, the commonest,
simplest, and least evolved type is that of the ordinary capsule, as in
the poppies and campions. At first sight, to be sure, a casual observer
might suppose there existed in these cases no recognisable device at
all for the dissemination of the seedlings. But you and I, most
excellent and discreet reader, are emphatically _not_, of course, mere
casual observers. _We_ look close, and go to the very root of things.
And when we do so, we see for ourselves at once that almost all
capsules open--where? why, at the top, so that the seeds can only be
shaken out when there is a high enough wind blowing to sway the stems
to and fro with some violence, and scatter the small black grains
inside to a considerable distance. Furthermore, in many instances, of
which the common poppy-head is an excellent example, the capsule opens
by lateral pores at the top of a flat head--a further precaution which
allows the seeds to get out only by a few at a time, after a distinct
jerk, and so scatters them pretty evenly, with different winds, over a
wide circular space around the mother plant. Experiment will show how
this simple dodge works. Try to shake out the poppy-seed from a ripe
poppy-head on the plant as it grows, without breaking the stem or
bending it unnaturally, and you will easily see how much force of wind
is required in order to put this unobtrusive but very effective
mechanism into working order.
The devices of this character employed by various plants for the
dispersal of seeds even in ordinary dry capsules are far too numerous
for me to describe in full detail, though they form a delightful
subject for individual study in any small suburban garden. I will only
give one more illustrative case, just to show the sort of point an
amateur should always be on the look-out for. There is an extremely
common, though inconspicuous, English weed, the mouse-ear chickweed,
found everywhere in flower-beds or grass-plots, however small, and
noticeable for its quaint little horn-shaped capsules. These have a
very odd sort of twist or cock-up in the middle, just above the part
where the seeds lie; and they open at the top by ten small teeth,
pointed obliquely outward for no apparent reason. Yet every point has a
meaning of its own for all that. The plant is one that lies rather
close upon the ground; and the effect of this twist in the capsule is
that the seeds, which are relatively heavy, and well stored with
nutriment, can never get out at all, unless a very strong wind is
blowing, which sweeps over the herbage in long quick waves, and carries
everything it shakes out for great distances before it. So much design
have even the smallest weeds put into the mechanism for the dispersion
of their precious seeds, the hope of their race and the earnest of
their future!
Public-domain text, read in full here on John Shaqi.
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