By far the commonest method of ensuring a wide distribution of a seed is
that in which the object is attached to some light, feathery substance
which prevents a speedy falling. Of this there is no better instance
than the common dandelion, which at seed time produces the handsome
“clock” so prized by the children.
Here each seed is attached to a feathery process which plays the part of
a parachute. On a dry day, when the dandelion heads are parting with
their fruits, we may see how well the scheme works. Each puff of wind
releases a few of the seeds, and these, unlike the ordinary parachute
with a load, are so light that they rise upwards on the air currents.
Curiously enough, the fruits seem to travel farther when the breezes are
light, and a very rough wind blows them back to earth, where they may
catch in the grass or become damaged. Thus, like the airman, the
dandelion seed stands the best chance of a safe journey when the weather
is not too boisterous.
A very similar arrangement is to be seen in the case of the goat’s-beard
fruit and that of the coltsfoot, which, by reason of its flying device,
secures a very wide distribution.