Blossoms which sleep at night 夜眠る花

That is a big plant in a flower bucket. Starting this year it was put in front of a house. Since June, blossoms have appeared one by one and now it is in full bloom. Recently when I passed by in the evening, I noticed that all the blossoms were closed. I pass by every day and I thought it could not be that all blossoms were withering. I thought “They are sleeping!”. And really the next day during daytime they were back in full bloom. How sweet! Do you know the name of this tree?

これは植木鉢の大きな木です。今年初めてある家の前に置かれました。6月からぽつぽつ花をつけ、今は満開です。この前を先日夜間に通りかかったところ、全ての花が閉じていることに気が付きました。毎日ここを通るので、一度に全ての花が枯れるとは思えませんでした。きっと夜になると眠る花なのだろうと思いました。次の日、昼間に前を通ったら、案の定、花は皆んな再び開いていました。かわいい!なんという木か、ご存知?

Picture by Yuka Simeno, August 2020 in Vienna