Dear Ken and All,
Indeed, viability of old seed is quite a fascinating subject
in itself.
A number of years ago the Sacramento, California Chapter of
the The California Native Plant Society, gave a multi-speaker program
on restoring a wetland area near Davis, California, a research
project studying the effects of different plantings on flood erosion
control on the American River and converting a small park east of
Sacramento to a Native Plant habitat. The latter speaker related his
experience with wild flower viability. In one part of the park, a
small area was graded preparatory to planting. Over the winter,
prior to the spring seeding, many many wild flower seeds germinated
that apparently had been dormant under the prior discarded soil.
Here is another example of the viability of some
seed. Several years ago my sister in Bend, Oregon, accepted a
friend's offer to rototill her vegetable garden where she had been
growing for several years. Subsequently, she found her garden thick
with the Common Purslane (Portulaca oleracea). She tried everything
she knew to do to eliminate the weed from hand pulling, hoeing (a
more efficient way to make cuttings of the little demon) to
glysophate. She said she would no sooner clear the area than another
set of weeds emerged. When I recently completed Master Gardener
training, I was able to verify her theory that her neighbor's
generous deed had been responsible. One Common purslane plant is
capable of producing 53,400 seeds that have a potential viability of 30 years.
Kind regards, Joyce Miller
Gresham, Oregon Zone 7