How do those vines do it?

[mslxl]

Vines grow by wrapping themselves around fixed objects and moving from one to the next. Cuttings of vines have been observed "reaching" for a branch or man-made object in their vicinity and wrapping themselves around them. How do they "know" of the presence of the object before they grow long enough to touch it? This is not growing toward the sun in some phototropic cellular mechanism. This is growing toward an inert object.

mslxl

[This Guy]

Vines grow by wrapping themselves around fixed objects and moving from one to the next. Cuttings of vines have been observed "reaching" for a branch or man-made object in their vicinity and wrapping themselves around them. How do they "know" of the presence of the object before they grow long enough to touch it? This is not growing toward the sun in some phototropic cellular mechanism. This is growing toward an inert object.

mslxl

I'll give a SWAG (Scientific Wild Azz Guess, OK, the S word my be arguable;-)

Could they be growing toward the shadow of a taller object? Perhaps because the side away from/out of the shadow grows faster, causing a bending over?

Interesting question. I'm eager to see what the smart people post :)

[Ladewig]

All the time-lapse films of growing vines that I have seen show the top of the vine rotating 360 degreees as it gets longer. The vine makes ever-widening circles as it extends itself; eventually it hits an object and depending on the diameter of the object wraps itself around it.

Maybe there is a short example on YouTube,