Onoclea sensibilis is a fern from a creeping, branching, rhizome, colonial; roots associated with vesicular-arbuscular endomycorrhizal fungi (Berliner and Torrey 1989).
Leaves deciduous, arising singly or few together along rhizome, to 1 m long, blade 20-60 cm long, 15-35 cm wide, bright green, sterile blades pinnate leaflets opposite, up to 12 pairs (Del Tredici 2010), lower leaflets often broadly toothed or lobed; midrib winged.
Spore cases bead-like, replacing leaflet lobes on stiff, shorter fertile leaves to 17 cm long, green, July-Aug, turning dark brown, persistent through winter.
Wetland status: FACW.
Frequency in NYC: Frequent.
Origin: Native to NYC.
Habitat: Open, or bright, wooded swamps and wet areas, neutral to subacid soil, but noted growing under Ilex opaca (American holly) in fairy deep shade (Gargiullo, personal observation).
Notes: Fronds eaten by some insects, wither quickly in drought or frost. Noted to be toxic to horses (Kingsbury 1964). A host of the white-spored fir rust fungus Uredinopsis mirabilis (a fir-fern rust, Basidiomycotina) (Sinclair et al. 1987). Quite tolerant of open, disturbed sites if soil is wet.