Distinctive features:
Leathery leaves, all parallel to the ground like louvered blinds.
Similar species: Spinulose Wood Fern (Dryopteris carthusiana) - usually thrice divided, and don't grow in such a wet habitat. Intermediate Wood Fern (Dryopteris intermedia) - usually thrice divided, and don't grow in such a wet habitat.
Fronds: Twice divided; Leathery leaves, all parallel to the ground like louvered blinds. But don't rely on just the louvering to ID this fern. Other ferns will sometimes do this.
This and the next three photos show the louvered aspect of the leaflets.
**BUT** do not use this feature alone to identify this fern. Other ferns sometimes grow like this. I've been fooled.
The key features of Crested Shield Fern are:
leathery leaflets;
grows in wet areas;
twice divided; louvered leaflets.
.
A young frond unfurling.
Spore dots (sori) on the underside of a leaflet. They're round and are lined up in two rows.
This photos shows the two rows of sori quite clearly.
PLEASE NOTE: A coloured Province or State means this species occurs somewhere in that Province/State.
The entire Province/State is coloured, regardless of where in that Province/State it occurs.
(Range map provided courtesy of the USDA website
and is displayed here in accordance with their
Policies)