Happy St. Patrick's Day!

Just as an oxalis acetosella update, I love this plant more and more.
One night I noticed it doing this weird thing:

See how the leaves droop and pinch together like they are depressed?  I panicked the first time I saw it, thinking it would lose all its leaves even before it could shine in all its glory on the very holiday it was meant to grace, but in the morning it was bright and perky again.

I noticed it doing the same thing the next night.  I realized it must just curl up like that on purpose when it wants to sleep for the night.  Isn't that cute?
Sometimes it reminds me of delicate green butterflies, the way it hangs and flitters.

Happy St. Patrick's Day!