The way a scarlet runner bean twists counter-clockwise up a cane

You’d think a bean would grow straight, but the scarlet runner is a stubborn climber. Every vine spirals counter-clockwise, wrapping around the cane like a frantic green corkscrew.

It’s not just being picky. One side of the stem grows faster than the other, forcing the tip to sweep in circles until it hits something solid. It’s a trick called circumnutation—basically the plant hunting for a grip.

Try to force it clockwise and it’ll just untwist itself. It’s hard-wired left-handedness, a biological motor that refuses to follow any other map.

Wait, so every climbing plant is a 'leftie' like this bean?

Not by a long shot. While our runner bean is a dedicated 'leftie,' other plants like hops are staunch 'righties.' They’ve each picked a lane and they’re sticking to it. It’s not a whim; it’s a genetic blueprint handed down through generations.

Think of it like a specialized tool in the shed. One species evolved to turn one way, and another went the opposite. They don't switch it up for variety—if you’re a clockwise climber, you’re born, live, and end up in the compost heap turning that same way.

Does that mean a bean seed 'knows' its direction before it even sprouts?

Spot on. That seed isn't waiting to see which way the wind blows. The instructions are packed inside like a pre-set clock. Before it even breaks the soil, the blueprint for that spiral is already active.

It’s down to how hormones are distributed in the tiny stem. They tell one side to stretch while the other lags, creating that inevitable curve. It’s a mechanical result of its chemistry.

You could try to trick it with fancy lights, but you’re fighting millions of years of stubborn evolution. Once written, the plant is a committed one-trick pony.

If I plant the seed upside down, does it get confused?

Nice try, but you can't prank a bean that easily. Even if you bury it upside down, the plant has a built-in spirit level. Tiny starch grains sink to the bottom of its cells, telling the hormones exactly where to pool so the shoot heads for the sky.

Once it knows which way is 'up,' the spiral program kicks in. It’s like a GPS that recalibrates the moment you turn the key.

You could spin that pot like a top, and the bean would still find the sun. It’s not looking at a map; it’s feeling the pull of the earth itself.

What happens if you try growing one of these in space?

You’re talking about a gardener’s nightmare. Without gravity, those starch grains just float around like lost marbles in a jar. The plant loses its sense of 'down' entirely.

It’s a right mess. On the Space Station, they have to use bright lights to trick the shoots into heading the right way. But the roots? They just wander about like a confused tourist without a map.

Even then, the spiral gets wonky. Without the earth's tug, the vine doesn't know how tight to coil. It’s proof that even the toughest climber needs grounding to stay on track.