flower non flower

I passed the exam. This provides enough motivation to stick with it and keep going to Danish school.
As I've nearly gone through yet another supply of batteries for the flash, I thought I should go out to take pictures. I found just a little more juice in the batteries instead.

This plant's leaves close up at night and spread out during the day.
In spite of its "louder" display before dark, I tend to give more attention to it at night.

Anyone knows what it is known as?