Plants need sleep, too!

Recently in Finland, and Austria scientists used laser sensors on Silver Birch trees to record branch movements. They found that at night tree branches droop...the trees go to sleep.  
A lot of flowers will also be open during the day, and close at night.   

http://m.mentalfloss.com/article.php?id=80275




Peony 'Moon Rise' during the day. This is always my first peony to bloom each Spring.



Same peony as above, but at dusk.