Osmunda cinnamomea Linnaeus
cinnamon fern
Family: Osmundaceae

sterile frond
fertile frond
crozier ("fiddle-head")

Osmunda cinnamomea is a large fern with a conspicuously clumped growth form and separate and dramatically different fertile fronds. The sterile fronds often reach a length of 1 meter in our area (range 0.3-1.5 meters) with pinnate-pinnatifid blades. Fertile fronds are shorter and much narrower than the sterile fronds and when they mature (mostly in June in the north, perhaps late May in the south) they change from green to a bright orange-brown color from which the common name is derived. Once spores have been dispersed the fertile fronds quickly wilt and fall to the ground where they become quite inconspicuous. Sterile fronds of O. cinnamomea can be distinguished by a small area of wooly hairs on the under (abaxial) surface at the base of the pinnae, that is lacking in the similar O. claytoniana. Matteuccia struthiopteris is similar in size, but also lacks the wooly hairs at the pinna base and the fronds are long tapering at the base with the lowest pinna much less than half as long as the longest pinnae. O. cinnamomea is slightly tapered to the base, but the lowest pinnae are more than half as long as the longest pinnae.

O. cinnamomea is widely distributed in eastern North America, ranging from Ontario and Minnesota to Texas and east to Florida and Labrador. It is common throughout Wisconsin in a variety of at least seasonally wet habitats, often (though not always) with somewhat acid soils.

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