Persistent Fertile Fronds

Persistent Fertile Fronds

My winter walks are often focused on lichens, winter tree ID and birdwatching (birds are so much easier to see when there are no leaves in your way!). But every now and again there’s an interesting unexpected sighting. With the exception of a few species of evergreen fern, notably Christmas fern, rock polypody and evergreen woodfern, winter is not generally a good time to locate and identify ferns. But there are a couple species that have parts that are persistent through the winter. The netted chain fern (Woodwardia areolata) is one of these. 

Found in shady, acidic swamps and wet woods, the sterile leaves of netted chain ferns resemble those of sensitive fern (Onoclea sensibilis), but are a glossier green with wavy, fine-toothed leaf margins and are more pointed at the tip. Netted chain ferns leaves are also smaller overall than sensitive ferns. The leaf veins are prominently raised and form a conspicuous netted pattern, giving the species its common name. 

Sterile leaf of the netted chain fern (photo taken in September).
Fertile frond of netted chain fern (photo taken in September).

As a deciduous fern, by late February and early March the leaves have long since faded. The fertile fronds, however, often persist upright through the winter. The fertile fronds are narrower and more widely spaced than the sterile leaves, and leaflets have linear lobes that are often recurved over rows of chain-like oval fruit dots. (By contrast, sensitive fern has beaded, woody-like fertile fronds). The persistent winter form of the fertile fronds were photographed a few weeks ago at Ryder Conservation Area in Sandwich.

Over the next couple of months, as you pass by wetland edges on your woodland hikes, see if you can spot evidence of ferns, like the fertile fronds of netted chain fern or sensitive fern. 

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