October 8, 2016
As the old song goes, birds do it; bees do it—“it” being pollination, of course.
What exactly is pollination and how does it happen? If you’re picturing a bee carefully carrying pollen from the male part of the flower (anther) to the female part of the flower (stigma), you’ve got the process and the flower parts right, but it turns out there’s nothing deliberate about pollination. In fact, it’s just dumb luck.
The real reason a bee visits a flower is because it’s hungry. It may be collecting pollen to bring home to the hive, but more often it’s out for a bite to eat. Sipping nectar gives bees energy, and if they’re honey producers, nectar is the main ingredient.
Most flowers have markings called honey or nectar guides. Like the stripes on a runway guiding 747s at SFO, these guides tell bees where to land, where to taxi and where to go for nectar. These nectar guides are a clever flower ploy to make sure that bees pass by the pollen on their way to the nectar. With a flower like the iris, we can see the nectar guides, but most are invisible to the human eye because they are ultraviolet. Fortunately, bees have no problem seeing ultraviolet markings.
When bees make contact with a flower’s anther on the way to the yummy nectar, the pollen is drawn to the hairs on the bee by static electricity. Remember as a kid when you rubbed a balloon on your head to stick it to the wall? It’s the same basic science. Only it’s much cooler when bees do it.
The sparks keep flying as bees zip through the air to forage on a feast of flowers, unwittingly losing electrons and gaining a positive charge. Flowers on the other hand, have weak negative charges. Since opposite charges attract, the negatively charged pollen adheres to the positively charged bee, which sets the stage. The stigma of a flower, that’s the female part, has a sticky substance that catches the pollen as the bee brushes by, and that’s when pollination happens. This can occur on the same plant, or on another plant of the same species that a bee visits — that’s called cross-pollination.
Static charge also helps a bee decide which flowers to visit. When a bee lands on a flower, its strong positive charge switches the weak negative charge of the flower into a positive charge for about 100 seconds. Amazingly, that’s how long it takes a flower to refill its nectar glands that were just emptied by the bee.
If another bee comes along in that 100 seconds, it will feel the flower giving it the brush off. That’s because the nectar-generating flower has a positive charge instead of the negative charge the bee was expecting. Think of it this way: when you played with magnets as a child, what happened when you tried to put two positives together? They wouldn’t join. But positive and negative magnets? They stuck together perfectly.
You don’t have to be a scientist to appreciate bees, yet the science is pretty remarkable. What’s equally remarkable is the importance of bees, which account for one out of every three bites of food we eat.
To learn more about these fascinating creatures, how to attract them to your garden and how they are under threat come to my free talk at “The Secret Life of Bees” 11 a.m. Oct. 15 at the Novato Library at 1720 Novato Blvd., Novato, and 7 p.m. April 6 at the Larkspur Library, 400 Magnolia Ave., Larkspur.