Here’s a wonderful tidbit from a book that every physics teacher should have — The Flying Circus of Physics. My old mentor PD gave it to me with the inscription, “until I write my book of physics stories, this is the best collection of science stories in print.” As much as I love Paul, I think even he’d have a big task to outdo the wide array of stories and strange facts in this book (though I’d love to see him try!). Need something to spice up a lecture on sound? How about an explanation of why we hear our upstairs neighbors more than they hear us? Or need a story to make the idea of pressure come alive? How about the girl who got her tongue stuck in a bottle and needed glass cutters to help her get free?
So here’s the story of how electricity helps flowers grow. We generally think of pollination as being a sort of accidental process — the bee gets himself all covered in yellow snow at one flower, and then loses some of it at the next flower. No, it turns out that bees get positively charged (they lose some electrons) as they fly through the air. When the positive bee approaches the neutral flower, that induces a charge in the pollen, which jumps onto the bee.
This is the same phenomenon as when you rub a balloon on your sweater. The balloon becomes positively charged and when you bring it to the wall, it induces a charge in the wall. Thus, it sticks to the wall. There’s a nice simulation of this effect here.
Anyway, the pollen sticks to the hairs on the bee. If it stuck to the bee itself, it would lose its charge. The hair acts as an insulator, keeping the pollen grain just far enough away to keep it charged, and thus attracted to the bee.
Now, when the bee goes to the next flower, it induces a negative charge in the stigma of that flower. The pollen grains are more strongly affected by that concentrated negative charge (the stigma, after all, has more charge than the bee, it’s connected to the ground so has an infinite source of electrons to draw from), and the pollen grain is polarized in the opposite way and jumps to the flower.
Wow. I wonder if pollination doesn’t work as well in moist climates, then? Is that why Colorado wildflowers are so stunning in their concentrations?