Last night was the coldest night so far this winter. It was 24f this morning. When the temperatures are this low many plants have the unusual response of curling their leaves.
This is known as a thermotropic response. There are many theories to why some plants do this: 1) Photo inhibition to reduce winter damage from radiation, 2) heat balance theory to maintain temperature, 3) freezing damage theory to prevent damage from rapid thawing after freezing, 4) mechanical theory to prevent damage to the leaf, and 5) desiccation theory to prevent the leaf from drying out are all theories as to why leaves curl in cold weather.
So many theories!
Some plants in my garden which commonly do this are:
The chain link fence which runs around the entire half-acre was planted by the previous owner with wintercreeper and is now covered and trimmed to resemble a hedge. The previous owner, who lived in the house for thirty years, did this many years ago and I thank her.