Fern ID: Interrupted Fern

At first glance, Interrupted Fern (Osmunda claytoniana) appears much like Cinnamon Fern. Both are typically tall, have twice-pinnate fronds* and grow in circular clumps often in moist soils. But whereas Cinnamon Fern has non-leafy, spore-bearing fronds that grow in the center of clusters, Interrupted Fern produces spores mid-frond, between green pinnae (for photos of these brown interruptions, visit Go Botany).

Photo of Cinnamon Fern reverse

In the absence of fertile fronds, check the undersides of the pinnae where they meet the stalk:  Cinnamon Fern (above) has small tufts of fuzz near this junction, which Interrupted Fern (below) lacks.

Photo of Interrupted Fern reverse

*Ferns typically feature fronds that are pinnate, twice-pinnate, or thrice-pinnate.  In the case of both Interrupted and Cinnamon Fern, fronds are twice-pinnate, meaning each frond is divided into primary leaf segments (called pinnae) which are further divided into leaflets (called pinnules).

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