What plant is that?

The December mystery plant differs from most other Mystery Plants in that it has no flowers. Instead of flowers it has spores produced on the underside of the frond. The fronds on this plant are evergreen, leathery and each plant forms a circular clump. The fronds are divided into leaflets called pinnae which are shaped like stockings. The stems may be covered with thick hair-like scales. This plant is found in woods and on rocky slopes. A winter favorite!