Advice from a Naturalist: Christmas Fern

November 20 2023

After the last leaf has fallen and other plants have died back for winter, the Christmas Fern (Polystichum acrostichoides) brings a touch of green to the forest floor all winter with its evergreen fronds. Named for these fronds that persist through Christmas and all winter long, Christmas Fern is native to the eastern United States, and I have observed them all the way from Florida to Maine.

New fertile fronds (with spores on the back side) and sterile fronds (without spores) appear in spring, but it is the sterile fronds that last through winter, even if they are flattened by snow or falling leaves. In warm seasons, Christmas ferns can be differentiated from other common local ferns, such as Cinnamon Fern or Sensitive Fern, by its dark green 12 to 30 inch fronds which have distinct finely serrated leaves called pinnae. The pinnae are about 1 ½ inches long and have small, triangular, thumblike lobes at the base.

Good local places to look for Christmas Ferns include the Cross County Trail and Seneca Regional Park, where they can be found in wooded area and stream banks.


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