Thursday, April 11, 2013

coated in pollen

Scanning electron microscope image of various grains of pollen

Pollen. Pollen. Pollen.

Don't you just love it? Hard yellowish grains—so tiny you need a scanning electron microscope to see them—often covered with barbs or spikes or hooks or razor wire or shards of glass, that's pollen. They look like the morning star flails the medieval knights used and the hard prickly cover helps the pollen stick wherever it lands. It also protects the sperm cell hidden inside. 

It’s estimated that 35.9 million Americans have pollen allergies, so I’m not alone. Every spring we get together and have a party in the antihistamine aisle of our local pharmacy.

Plants have a big problem when it comes to reproduction: the males and females cannot cozy up to one another. Cozying leads to canoodling which makes reproduction easier. Perhaps you've already noticed. But since plants are stationary, how do the male pollen grains and the female egg cells get together? 

There's a serious lack of canoodling in the plant world. Somehow they need help. Basically, either a creature like an insect carries the pollen from male part to female part or the wind transports the pollen.

If a tree has a showy flower, like a dogwood or apple, then they rely on insects. 

Generally, this pollen doesn’t bother most allergy sufferers because it’s heavy and sticky in order to bond itself to the insects’ bodies. It doesn’t float around freely for us humans to inhale.

The trees that rely on the wind for pollination, like the maples, birches, cedars, hickories, oaks and pines, do not have showy flowers. They don’t need them. These trees have to produce tons of tiny, lightweight, barb-covered pollen grains because the wind is a sloppy messenger. It’s actually quite messy.

It is estimated that a single male flower—called a catkin—on a birch can produce 5.5 million grains of pollen. And, there can be thousands of male catkins on a single tree. If you do the math, that's roughly a double quad-zillion grains of pollen per tree with a zillion being defined as an extremely large, indeterminate amount. Most of the pollen seems to find either my car, turning it yellow, or my sinuses, turning them achy.

Or perhaps locally they land in Norris Lake to float harmlessly downstream to the Mississippi.

A yellow wave of pollen on Norris Lake.  Photo by Don Bickers.

Thanks, Lynne, Don.

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