Onoclea sensibilis L. - Sensitive Fern


 

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Onoclea sensibilis - (image 1 of 6)

 

Taxonomy

Family: Dryopteridaceae

Habitat

Marshes, boggy woodlands, moist parts of mesic woods, and along the muddy borders of shaded pools.

Associates

 

 Distribution

Throughout the eastern half of the U.S. and southern Canada.

Morphology

Perennial from a long, branching rhizome. Leaves to 1 m; blade to 40 cm, deeply pinnatifid; rachis broadly winged except near the base; leaf segments opposite with 8-12 pairs, glabrous above, with scattered white hair on the veins below; fertile leaves with inrolled, globular pinnules to 4 mm wide, persisting throughout winter.

Notes

Fertile leaves produced early September to early October.

Wetland indicator: Facultative Wetland

The name Sensitive Fern relates to the tendency of the sterile leaves to collapse after the first hard freeze, as if "sensitive" to the cold. When the plants are mowed or otherwise injured the fertile fronds tend to look like the sterile fronds and this can be considered f. obtusilobata. The center frond in image 2 might be representative of this form.

References

Cobb, B. 1984. A Field Guide to Ferns and Their Related Families.
Houghton Mifflin Co., New York, NY

 

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.

The New York Botanical Garden. Bronx, NY

 

Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.
 


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 Michael Hough 2005