How do vines 'know' how to wrap themselves around a host stalk or post?

We had morning glories that would wrap themselves around other plant using the right hand rule. There were more wraps than days so they plants are not following the sun. Also about one plant in 20 would wrap using the left hand rule. What is up with that?
I am in the Northern hemisphere so I eagerly await a report from an Aussie on this one.

Well, it’s not so much that they “know”, but if you look closely at vine-type plants, particularly the shoots that are hanging loose in the air (and not attached), you’ll see that they curl naturally. I’ve noticed this most recently with our wisteria and my mom’s zucchini plants.

Having something to curl around is, of course, just a matter of chance. Stems grow outward.. basically, the base of the stem is older than the tip, as I’m sure you know. But from the base, the cells divide upward/outward creating new growth. So any part that may have wrapped or curled around something will stay put because it’s done growing. The tip of the shoot will continue to extend and continue to curl naturally.

I am a vineaholic!

I spend hours in the summer training all my Morning Glory vines to twine the way I want them to. lol

@Coloma I’m not sure if you are kidding or not but have you noticed the 5% lefties? There’s a doctoral thesis waiting for someone.
Be sure to credit me.

Some climbers seem to have suction-cup type things on ‘em… My sister had a viny plant of some kind on a high shelf, and I guess she didn’t turn it or move it often. One day she moved it, and the vine, which had been following the wall, was actually stuck to the wall. When she pulled it off there were little green bits stuck to the wall where the vine had stuck itself on.

GA, @MissAnthrope.

Now that you mention it, I have noticed that ‘pigtail effect’ on the growing ends of squash and cucumber vines. But strangely, I don’t think that I’ve seen it on the ‘weed’ type vines that I have running riot around my hedges. I’ll look closer next time.

It still seems odd that no matter how the tip gets pushed, blown, moved by other leaves, etc., it still seems to curl in the same way.

@Coloma

You have waaaaaaay too much time on your hands if you’re training morning glories how to twine. I spend literally minutes every week of the growing season pulling them up by the roots.

@worriedguy

Waiting for reports from Oz.

@Seelix

Yeah, some of the vines that try to creep up the walls of my house grow actual roots. But it’s funny how those roots are always oriented on the side of the vine that needs them. They never grow from the opposite side of the plant and wrap around the vine stem to attach. How did they know where to grow?

@CyanoticWasp

Heh..well, mine go crazy and if I don’t keep training them they wrap around my graveyard gates and they won’t open.
It’s like an alien invasion, night of the vines, overnight the whole house is entwined. lol

Start reading on page 76. Second Paragraph.

Thanks, @breedmitch. Interesting reading.

Climbing vine tendrils have cells that are sensitive to touch. When they touch something, the cells in contact inhibit release of their growth hormone. The cells on the other side of the tendril, not touching anything, grow faster. Hence the tendril curls tightly around whatever it comes into lasting contact with.