The process undergone by the seeds of some
plants before germination can occur. The
length of the after-ripening period in
different species may vary from a few weeks
to many months. It helps seeds to germinate
at a time when conditions are most favourable
for growth. In some cases the embryo is not
fully mature at the time of dispersal and
must develop further before germination can
take place. Other seeds do not germinate even
when the embryo is mature, probably owing to
growth-inhibitors within the seed which must
be leached out or broken down before
germination can begin.