Does this plant... behavior have a name?

Factual Questions
1

I have a pretty little cluster of bonsai trees. Two of the trees are Sweet Thorntrees, and they have this one trait that at first alarmed me. At night, the leaves fold up and droop. They have long narrow branches with leaves fairly equally space on either side, and at night, the leaves fold in such a way that they look sort of like folded hands.

Now I’ve seen plants that close up when you touch them (thigmotropic, if I remember correctly) but aside from dandelions I haven’t seen anything so affected by sun or lack of it. Is there a name for it?

2

Nyctinastic movement.

You can see it Mimosa plants.

3

Cool, thank you.

Does the response happen quickly enough to be visible to the watching eye? I’ve always meant to try and remember to keep an eye on it at sunset but never do.

4

Yes, it usually happens in a second or two. I’m not sure if the whole plant reacts at once or if different parts react whenever the light level drops below some value.