Osmunda cinnamomea

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Osmunda cinnamomea

Sterile fronds in late summer

Scientific classification

Kingdom:	Plantae
Division:	Pteridophyta
Class:	Osmundopsida
Order:	Osmundales
Family:	Osmundaceae
Genus:	Osmunda
Species:	O. cinnamomea

Binomial name

Osmunda cinnamomea
L.

Osmunda cinnamomea (Cinnamon Fern) is a species of fern in the genus Osmunda. It is native to the Americas and eastern Asia, growing in moist woodlands.

Close-up of the pinnae of a sterile frond

In North America it occurs from southern Labrador west to Ontario, and south through the eastern United States to eastern Mexico and the West Indies; in South America it occurs west to Peru and south to Paraguay. In Asia it occurs from southeastern Siberia south through Japan, Korea, China and Taiwan to Myanmar, Thailand and Vietnam.

It is a deciduous herbaceous plant which produces separate fertile and sterile fronds. The sterile fronds are spreading, 30-150 cm tall and 15-20 cm broad, pinnate, with pinnae 5-10 cm long and 2-2.5 cm broad, deeply lobed (so the fronds are nearly, but not quite, bipinnate). The fertile spore-bearing fronds are erect and shorter, 20-45 cm tall; they become cinnamon-colored, which gives the species its name. The fertile leaves appear first; their green color slowly becomes brown as the season progresses and the spores are dropped. The spore-bearing stems persist after the sterile fronds are killed by frost, until the next season. The spores must develop within a few weeks or fail.