Have you ever wondered how that morning glory vine knew how to find a support and twine around it? Or, for that matter, how roots know to grow down and stems know to grow up? And while we all know that plants follow light – how exactly do they do that?
For those of us who enjoy our geekery, it’s fun finding out more about these things. But even if you’re not a geek, knowing how your plants move adds a dimension to gardening, and might help you garden better, too. And just about everyone loves watching time-lapse photography movies, which are the core of this post. You can watch plants dance.
The forces that move plants really are beyond our ken. Well, the forces of nature are pretty much beyond our ken (especially our own natures). But humans do like to watch and name things. Science (one of the big areas for watching and naming, but not the only one) – science has a name for the ways plants move: tropisms.
There are different kinds of tropisms, but I think it would be much more fun for you to watch them than for me to tell you about them. This Indiana University site has several very short movies – each of them less than a minute. You can watch corn sprouts bend down, worshipping light in a ceremonial circle, or corn roots that know which way is down, even when they’re turned on their sides. Arabidopsis and tomato sprouts gracefully quirk into arabesques toward different kinds of light. Take five minutes at the Plants in Motion website; it’s better than a coffee break for a rush of energy.
Morning glory flowers lean into the sun: phototropism
My favorite movements are what this site calls nastic movements, movements plants make which aren’t necessarily in the direction of the stimulus (roots going down to ground, stems bending toward light). If you go to this page of the site, you can watch a morning glory vine wave around, find a support, and twine around it.
Of course since it’s human beings making the categories here, there’s some argument about whether this is a nastic movement – those are the movements that don’t go toward (or away from) the stimulus. Some people call this dance of the morning glories thigmatropism – which means that when the reaching plant hits a solid object, it starts twining (or in the case of plants with suction cups, like ivy, sticking).
If you like intimations of horror without the gore, there’s an episode of a venus fly trap closing (a nursery manager once taught me how to stimulate the center, not the edges, of their traps. And using a bigger instrument (such as your finger) will get you better results than the little metal tool in this movie).
To me, the most spectacular of these nastic movements are the young and old arabidopsis (what is arabidopsis?) plants. They wave, they bend, they whirl: what’s the force moving them? Their own plant cells, elongating more on one side than another. When you watch the 10-second movie, they look as if they are blowing in a high wind. But the wind is all inside them. Inside their secret lives.