Last updated on April 17, 2014 at 12:35 EDT

Interrupted Fern, Osmunda claytoniana

The Interrupted Fern (Osmunda claytoniana), is a fern native to eastern North America and eastern Asia. In eastern North America it occurs from southern Manitoba, Ontario, Quebec (up to the tree line), east to Newfoundland and south through the Appalachian mountains down to Georgia and west to the Mississippi River. In Asia, it is found in the Himalaya, southern China, Japan, Korea, and Taiwan. It is found in humid zones, mostly in forests, but also in more open biomes, although rarely in bogs. The interrupted fern is often found alongside ostrich, cinnamon and sensitive ferns.

The fronds are bipinnate, 16 to 40 inches tall and 8 to 12 inches broad, the blade formed of alternate segments forming an arching blade tightening to a pointed end. The lower end is also slightly thinner than the rest of the frond because the first segments are shorter. Three to seven short, cinnamon-colored fertile segments are inserted in the middle of the length, giving the plant its name. In their absence, the plant in all its stages is extremely similar to Osmunda cinnamomea (Cinnamon Fern). To distinguish them, look at the base of the segments where O. cinnamomea has typical felt-like hairs, the few hairs present on O. claytoniana are extremely short, usually requiring a magnifying glass to see well.

Like other species in the family Osmundaceae, it grows a very large rhizome. It forms small, dense colonies, spreading locally through its rhizome, and often forming fairy rings. The plant is known from fossils to have grown in Europe, showing a previous circumboreal distribution. Unlike those of the ostrich fern, the interrupted fern’s fiddleheads are not readily edible, due to their bitter taste and a tendency to cause diarrhea. The stalk and very young buds are edible, but should not be abused for risk of killing the crown.

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Interrupted Fern Osmunda claytoniana