It was so cold at our house yesterday (11˚F) that the leaves of the rhododendrons had curled up to protect themselves, a phenomenon called thermotropic leaf movement that was first described by Charles Darwin.
You can see the photo from yesterday, and read a bit about thermotropic leaf movement, here: http://quodlibet-sarah.blogspot.com/2012/01/darwin-and-rhododendrons.html
Last night we got the first snow we’ve had since Hallowe’en ― just an inch and a half, but enough to touch almost everything, including the rhododendrons, with white.
But it’s a lot warmer this morning ― 34˚F ― and though the rhododendrons are snowy, they’re not curled up. In fact, the snow protects and insulates them: