Nature Bulletin No. 507-A   November 17, 1973
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

****:VIABILITY OF SEEDS

A viable seed is one capable of germinating and producing a new plant, 
The question of how long seeds can remain dormant and retain their 
viability -- still be able to sprout -- has interested botanists, naturalists, 
foresters, and gardeners for many years but there is much more to be 
learned about it. A great deal of misinformation has been given to the 
public, such as fanciful yarns about wheat sprouting after its discovery 
in ancient Egyptian tombs. The maximum viability of wheat is about 30 
years -- usually far less.

Actually, many seeds are notoriously short-lived. Those of willows and 
poplars must lodge in a favorable spot and germinate within a few days 
after ripening, or they will not germinate at all. Nurserymen say also 
that cottonwood, silver maple and American elm seeds should be 
planted within two weeks after ripening, and their ability to germinate 
decreases rapidly. Ash seed may be stored until the following spring. 
White oak acorns must be planted as soon as gathered, whereas bur, 
red, black, and pin oak acorns need not be planted until the following 
spring if stored under proper conditions of temperature and moisture.

The Garden Dictionary lists corn, dandelion, onion, and parsnip seeds 
as having an average viability of two years. Beet, carrot, lettuce, squash, 
turnip, and watermelon seeds remain viable for an average of 5 or 6 
years but under ideal conditions may exceed 10 years. Cucumber and 
endive seeds are good for 10 years at least.

Our forest preserve plantsmen have found that hickory nuts and black 
walnuts remain viable after two years or more in storage and should be 
planted, as they are buried by squirrels, shallow. Their germination 
depends not only upon the moisture and warm sunshine in spring but is 
benefited also by freezing. That seems to be true of other plants. In our 
nursery the seeds of the Kentucky coffee tree, linden, cherries, and 
viburnums are "stratified" in autumn: layers of those seeds are placed 
between alternate layers of sand in an open pit. Exposure to the rain, 
snow and freezing during winter causes them to germinate more readily 
when planted in spring.

Seeds with hard coats tend to be long-lived. That is noticeable among 
the legumes -- which include the Kentucky coffee tree -- the mallows, 
and especially, the lotus. In the Illinois River Valley there used to be 
colonies of American lotus in swamplands now included in drainage 
districts which have been levied, pumped dry, and cultivated for 
decades. The farmers often uncover lotus seeds that are as hard and 
viable as they were 50 years ago. Lotus seeds collected from ancient 
lake beds in Manchuria have been established, by the Carbon 14 
method, as being from 830 to 1250 years old. After thinning the shells 
with a file, they were planted, some sprouted, and some produced 
flowers.

It has been demonstrated that, under ideal conditions of temperature, air 
and humidity, other kinds of seeds may remain viable after lying 
dormant for a long, long time. During the air raids of 1940, the Natural 
History Museum in London was badly damaged. Due to heat from fire 
and water used to put it out, a number of seeds -- stored there in 
drawers -- germinated, including some from a silk tree which had been 
collected in China in 1793.

In 1879, at Michigan State College, a lot of seeds were buried 20 inches 
below ground in uncorked bottles. Fifty years later, they were taken up 
and what kinds of seeds germinated ?

Mostly weeds.