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Back to June 1018 Newsletter

Pole Beans are Right-handed, Runner Beans are Left-handed

Bob Wildfong

What? "Pole beans are right-handed"? That's a peculiar starting point for a vegetable. What I mean is that their vines climb in a right-handed way.

Let me explain. If you look at a climbing bean on a pole, the vine always winds around in the same direction. Every vine of every pole bean climbs up and around to the left, or to the right if you look at it from underneath. That is, clockwise if you're looking from below but counter-clockwise if you're above. Sorry, that's confusing.

Here's a better way to say it. Hold out your right hand with the thumb pointing up and curl your fingers a little. Yes, do it right now while you're reading. That's the way pole beans climb. The tip goes up, like your thumb, and winds around in the direction of your fingers. If you put your right hand around the pole, you'll find the vines will curl just like your fingers do.

It's kind of amazing that all pole beans wind the same way. What could cause that? Some experts have explained that it's because the vines are following the direction of the sun, but that doesn't seem to explain it because pole beans wind themselves quite well on cloudy days, and if they're in partial shade so they can't see where the sun is. Also, there are many other kinds of vines that wind the other way.

Runner beans, for instance, are left-handed. That means they curl like the fingers of your left hand, when you point that thumb up. Amazingly, they all go the same way regardless of sunlight, and they don't seem to care that they wind differently than their right-handed cousins.

Why does this matter? Besides being a fun fact, it does help to know which way your vines prefer to curl when you're training them onto a support like a trellis or fence. I recently transplanted some hops, and as they tend to do, the vines grew out in all directions. Very gently, careful not to break the brittle tips, I wound them around the fenceposts to get them started in the right direction (up). Unfortunately, I guess I wound them the wrong way because by the next morning they had unwound themselves to lay all over the ground again. It turns out that hops are left-handed, so when I put them up that way they stayed put - and now they nearly cover the fence.

Have some fun inspecting climbing vines this summer. See which way morning glories curl. How about clematis? Ivy?

And I wonder if they go the other way in the Southern hemisphere?



Bob Wildfong is Seeds of Diversity's executive director. He is right-handed.


Back to June 1018 Newsletter

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