Unlikely as it may seem, some ferns are easy to find despite a several-inch blanket of snow. Most ferns emerge in April, grow spores under their fronds in the summer, scatter them, and lose the fronds after the frost. But SENSITIVE FERN, Onoclea sensibilis, (A) and its cousin OSTRICH FERN, Matteuccia struthiopteris, (B) have a different strategy. They grow separate short fertile fronds in mid-summer and then hold most of the spores through the winter, after the green sterile fronds have died. They then release their spores early the following spring, before other ferns have the chance. You can see the erect fertile fronds, brown stems with rows of beads, even in January if the snow isn’t too deep. Look in swampy or wet areas; they are very common. They even invade damp areas of lawn sometimes. Ostrich fern is relatively uncommon in eastern Massachusetts, though it is common enough in damp areas north and west of here. Its fronds form the tightest vase of any of our ferns. They are widest near the top, like an ostrich plume. The leaflets get tiny towards the base, and almost reach the brown-scaled crown that shows above the ground. The fiddleheads that are sold as produce in this country are all ostrich fern.
More information about the Sensitive Fern
Lady Bird Johnson Wildflower Center