Onoclea sensibilis L.
Sensitive fern, bead fern, meadow brake
Sensitive fern is common in temperate regions of Asia and North America. Its common and species names reflects the fact that its fronds give out at the first sign of frost (though its roots remain intact for next spring). Onoclea, from Greek meaning “closed vessel,” refers to the closely rolled fertile fronds. This genus has only a single species.
Identification: This robust fern favors wet areas, where its roots put up irregular rows of erect or tilted fronds. Young stems are red, and the emerging “fiddleheads” are pale red. Sterile fronds are 8–40″ (20–101 cm) long, with 8-12 pairs of opposing light green pinnae (leaflets). Fertile fronds are 10–20″ (25–50 cm) long, composed of pinnae so tightly rolled up as to resemble beads—the sori are inside the rolled leaves. The “beads” are 1/16–⅛″ (2–4 mm) around. In winter, the sterile fronds die back and disappear, but the fertile fronds, now dark brown and hard, remain as an unmistakable sign of this species.
Habitats: Swamps, wet areas, marshes, or low woods.
Online References:
References:
4/19/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts 
4/6/2021 · Otter Brrok Preserve, Harpswell Heritage Land Trust, Harpswell, Maine · ≈ 3½ × 6″ (9.5 × 14 cm) 
5/29/2010 · Maine Audubon Gilsland Farm Audubon Center, Falmouth, Maine 
5/4/2017 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 10 × 6″ (24 × 16 cm) 
7/6/2026 · Head of Tide Park, Topsham, Maine 
8/6/2014 · Shieling Forest, Peterborough, New Hampshire · ≈ 12 × 8″ (31 × 21 cm) 
4/8/2010 · Nashua River Rail Trail, Ayer, Massachusetts · ≈ 6 × 9″ (14 × 22 cm) 
6/15/2010 · Garden in the Woods, Framingham, Massachusetts · ≈ 2 × 1′ (62 × 41 cm) 
4/6/2021 · Otter Brrok Preserve, Harpswell Heritage Land Trust, Harpswell, Maine · ≈ 3½ × 6″ (8.8 × 14 cm) 
5/29/2010 · Maine Audubon Gilsland Farm Audubon Center, Falmouth, Maine · ≈ 2 × 1′ (62 × 41 cm) 
8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire · ≈ 4 × 6″ (10 × 16 cm) 
ID is uncertain 
6/8/2012 · Squannacook River Wildlife Area, Townsend, Massachusetts · ≈ 15 × 10″ (39 × 26 cm) 
5/29/2010 · Maine Audubon Gilsland Farm Audubon Center, Falmouth, Maine · ≈ 2 × 1′ (62 × 41 cm) 
6/15/2010 · Garden in the Woods, Framingham, Massachusetts · ≈ 11 × 7″ (27 × 18 cm) 
5/4/2017 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 5 × 6″ (13 × 15 cm) 
4/21/2021 · Center Pond Preserve, Phippsburg, Maine · ≈ 4 × 6″ (10 × 14 cm) 
4/21/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts · ≈ 6 × 6″ (16 × 15 cm) 
4/28/2014 · Big Bear Mountain, Brookline, New Hampshire · ≈ 6 × 9″ (16 × 21 cm) 
8/6/2014 · Shieling Forest, Peterborough, New Hampshire · ≈ 9 × 6″ (22 × 15 cm) 
5/2/2012 · Nashua River Rail Trail, East Pepperell, Pepperell, Massachusetts · ≈ 11 × 7″ (27 × 18 cm) 
4/23/2016 · Big Tree/Porcupine Trail, Beaver, Hollis, Massachusetts 
5/2/2012 · Nashua River Rail Trail, East Pepperell, Pepperell, Massachusetts · ≈ 8 × 6″ (21 × 15 cm) 
7/26/2025 · River Point Conservation Area, Falmouth, Maine · ≈ 12 × 8″ (30 × 20 cm) 
8/16/2014 · White Mountains, New Hampshire · ≈ 7 × 9″ (17 × 23 cm) 
8/8/2010 · Jeff Smith Trail, Beaver Brook Association Conservation Lands, Rte. 130, Hollis, New Hampshire · ≈ 4 × 6″ (10 × 14 cm) ID is uncertain 
| Kingdom | Plantae | Plants, but not fungi, lichens, or algae (from Stearn's Botanical Latin) |
| Subkingdom | Tracheobionta | Vascular plants—plants with a “circulatory system” for delivering water and nutrients |
| Division | Pteridophyta | Ferns |
| Class | Filicopsida | “Leptosporangiate” (has to do with how their spores form) ferns—includes most ferns |
| Order | Polypodiales | Polypod ferns |
| Family | Dryopteridaceae | Wood ferns (about 70% of the ferns) |
| Genus | Onoclea | New Latin, from Greek onokleia, anchusa |
| Species | sensibilis | From the Latin sentiō + -bilis, “perceptible, sensible, detectable” |
Onoclea sensibilis description by Thomas H. Kent, not updated.
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