Osmunda claytoniana L. - Interrupted Fern


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Osmunda claytoniana - (image 1 of 4)



Family: Osmundaceae


Moist woods and swamp margins, on neutral or subacid soil.




Throughout most of eastern half of the U.S. and Canada. Also occurs in eastern Asia.


Perennial. Leaves soft, dull green, clustered, to 1.5 m, the petiole densely wooly when young; blade pinnate-pinnatifid; rachis soon glabrate; outer leaves usually sterile; inner leaves larger, with 1-5 pairs of fertile pinnae near the middle of the blade; fertile pinnae much smaller than vegetative ones. Sporangia dark brown.


Spores late April to May.

Wetland indicator: Facultative +

The common name refers to the way the fertile pinnae occur near the middle of the frond. Can hybridize with O. regalis.



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.



 Michael Hough 2005