Juniper pollen goes far to perpetuate tree
Updated 12:33 pm, Friday, February 28, 2014
Now that the annual invasion of winter pollen is over, it's time to take a look at the life cycle of the responsible tree.
As you probably know, the pollen machine that causes so much misery each winter is the juniper, which is commonly known as the mountain or Hill Country cedar.
Junipers grow in Oklahoma, Kansas and Missouri, but their headquarters are in and around Central Texas.
Male junipers produce so much pollen that the sky over them can sometimes appear smoky or hazy. Female junipers need lots of that pollen, for a single mature tree can produce more than 100,000 berries.
Each berry includes a single seed. The seeds generally germinate after the berry that surrounds them has been digested by a bird or mammal.
There's another benefit from the trip through the gut of an animal, for it means the seed has a better chance of being deposited away from the parent tree and other junipers. The seeds in berries that fall to the ground under the parent tree have little chance of success unless washed into an open area by rain runoff.
The shedded leaves that form a thick layer under mature junipers tend to block the germination of juniper and other seeds. Should any sprouts develop, they will have little chance of survival in the dense shade of the thick juniper foliage.
Juniper seedlings do not grow well when shaded by grass. This is one reason the introduction of cattle, goats and sheep is blamed for the spread of junipers over the years.
Suppression of natural fires may also play a role, for small junipers are easily killed by fire.
Drought is a control method over which people have little or no control. Large numbers of junipers were killed by the recent drought and the drought of the 1950s.
These juniper facts are just a few of those described in “Biology and ecology of Ashe Juniper” by F.E. Smeins and S.D. Fuhlendorf, which you can find online by searching the title.
I close with a new fact. How high in the sky does juniper pollen rise on its way to distant destinations?
On Jan. 13, I was able to measure the altitude of a juniper pollen layer for the first time. That morning, there was a faint pollen corona around the sun. That evening I measured the brightness of the twilight sky and detected an unusual bump in the data about 9,800 feet overhead. Since the sky was very clean and clear, juniper pollen was the likely source, and it can travel a considerable distance at that altitude.
Forrest Mims, an amateur scientist whose research has appeared in leading scientific journals, was named one of the “50 Best Brains in Science” by Discover Magazine. His science is featured at www.forrestmims.org. Email him at email@example.com.