The Shield Ferns
The Christmas and Holly Ferns
Polýstichum
These have been grouped with the wood ferns, but are now usually placed under the genus Polýstichum, which has the sori round and covered with a circular indusium fixed to the frond by its depressed center. The wood ferns, on the other hand, have a kidney-shaped indusium attached to the fronds by the sinus. (Polýstichum is the Greek for many rows, the sori of some species being in many ranks.)