By Sara Wright
When I was growing up on my grandparents’ farm, my little brother and I found an abundance of Christmas ferns in the predominantly hardwood forest where we played. We loved these magnificent ferns because of their shapes. A fountain-like spray of forest green leaves with gray-green undersides that carried clusters of brown spores.
Christmas fern, an ancient 300-million-year-old plant, is long lived if left undisturbed. During the colder months these upright ferns lie flat along the ground still photosynthesizing, a strategy that allows the ferns to take advantage of a canopy opened by newly fallen leaves. In the spring fuzzy green fiddleheads arise from the center while last year’s leaves fade. Polystichum acrosticides is called the Christmas fern because it really does stay green all year long, even though in northern climates like Maine the ferns are buried under snow.
Today these ferns can still be found in both predominantly hardwood (maple and beech are favorites) and mixed forests that have been protected. Once disturbed by logging or heavy foot and machine traffic, the fern disappears.
The literature is very ambiguous about how common these ferns are. Some sources say that they are still abundant from Maine to New Mexico. Others say the ferns are endangered. We do know that once these ferns were found from Nova Scotia to southern Ontario, south to Florida and eastern Texas. This fern is listed as threatened in Minnesota and as a plant of special concern in Wisconsin. My field experience suggests that these ferns are slowly disappearing. Even in my forests I see them less frequently, and they do not appear to be reproducing like they once did. I also note that the clusters seem smaller overall. Although the few I have continue to thrive, they are not reproducing. At the moment, I have one large clump and two small clusters. All reproduce by wind born spores or from a central rhizome. A friend told me recently that he had found a large cluster in another protected forest, which indicates that in places with just the right ecology they may still be common.
Even in my forests I see them less frequently, and they do not appear to be reproducing like they once did. I also note that the clusters seem smaller overall.
Just this spring I rescued one from a recently logged forest. Because these ferns need shade and moisture to survive, any logging will kill them. I brought the withered fern home, soaked it, and replanted it in a pot with rich woodland soil, leaving it completely shaded all summer. It recovered, sprouting new fiddleheads by the time it went into the ground for good.
Christmas ferns are dimorphic, meaning that the fertile and sterile fronds are different. The former are taller, wider, and more erect. Only the upper portions of the fertile fronds have spores. When mature, the lower surface is covered by the spore bearing structures (sori). The buff brown spores are somewhat oblong in shape and are ready to be released by late summer or fall by light winds.
Because the Christmas fern is evergreen, it can be valuable as a food source for wildlife when little food is available. Deer, wild turkeys, ruffed and spruce grouse consume the evergreen fronds during both winter and spring. A few bird species, like ovenbirds and veery, use the overwintered fronds of Christmas ferns as nest sites. The Christmas fern is also a larval host for some worms.
The Christmas fern is classified as a Facultative Upland Plant (FAC), meaning that it usually occurs in non-wetlands, but in my experience, it also grows in wetlands with good drainage. In terms of site requirements, this fern is fairly shade tolerant but can tolerate sun if the soil stays moist.
Because the Christmas fern is evergreen, it can be valuable as a food source for wildlife when little food is available.
Look for it in shaded habitats, including woodlands, stream banks, and rocky slopes, all places with rich soil. As already mentioned, Christmas ferns are particularly fond of sugar maples and beech but can also be found among hemlocks that are not too mature. Once hemlocks mature and grow further apart, the soil can become too acidic for these ferns. Also look for Christmas ferns around hobblebush and striped maple leaved viburnum, all of which are understory plants. Canada mayflowers love to hide out in this type of habitat along with starflowers, wood sorrel, partridgeberry, foam flower, whirled wood asters, Indian cucumber root, wild sarsaparilla or ginger, Jack in the pulpit, and trout lilies.
Because these Christmas ferns are not as common as they once were, you are encouraged not to dig them up unless you find the remains of one in forests that have been logged. Any kind of canopy removal will heat up the soil and make it impossible for the fern to survive for long. Today, however, these ferns can be ordered online, and I encourage anyone who finds them as beautiful as I do to buy them this way. They make an absolutely stunning backdrop for shaded rock gardens with rich soil.