Onoclea sensibilis

L.

Sensitive Fern

Onocleaceae

Onoclea sensibilis is a species of fern in the family Onocleaceae. It is native to eastern North America, east of the Great Plains, and is widely cultivated as an ornamental.

Onoclea sensibilis

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Description

Onoclea sensibilis is a vigorous plant that spreads easily, often becoming weedy. Sterile fronds are a pale yellow-green, triangular, 13 to 34 cm long and 15 to 30 cm wide. Leafstalks are black near the bottom, 22 to 58 cm, flattened at the base. Sterile fronds are bipinnatifid. They have 5 to 11 lanceolate lobes on each side. Bottom lobes are 9 to 18 cm long, with smooth edges, or round or irregular lobes. Fertile fronds, produced from early spring to mid-fall, are green becoming black, narrow, 7 to 17 cm long and 1 to 4 cm wide. Leaflets roll under and eventually form black "beads" that are about 2 to 4 mm wide and hold the sori (FNAEC 1993). All parts of Onoclea sensibilis are toxic (Jacke and Toensmeier 2008).

Onoclea sensibilis is very similar to Onoclea interrupta, which is often considered a variety of this species. The two have subtle differences in their fronds: in Onoclea sensibilis, the sterile fronds are at least twice as long as the fertile fronds, and segments of the fertile fronds are closely spaced. In Onoclea interrupta, the fertile and sterile fronds are approximately the same length, and segments of the fertile fronds are widely separated. Additionally, Onoclea interrupta is found in northeastern Asia, while Onoclea sensibilis is found in North America (Gastony and Ungerer 1997). In North America, it can be confused with Woodwardia areolata without the presence of fertile leaves, but Onoclea sensibilis has pinnae with round or irregular lobes, while Woodwardia areolata has pinnate with smooth edges (FNAEC 1993).

Uses

Note: Please see the disclaimer regarding any information about medical or edible uses.

Onoclea sensibilis is sometimes grown as a garden plant. It tolerates wet soils well, and prefers relatively shadey soils. In its optimal conditions it can be aggressive (MBG).

Distribution

Onoclea sensibilis is common in wet areas like swamps, marshes, as well as thickets and woods. It often forms dense stands. It is found at an altitude of up to 1500 m. It is common in eastern North America, east of the Great Plains and from Newfoundland to central Florida (FNAEC 1993).

Status

Onoclea sensibilis is listed on the IUCN Red List as "Least Concern", citing a widespread range and little decline, which would not threaten its population (Maiz-Tome 2016).

References

Gastony, G. J., and Ungerer, M. C. 1997. Molecular Systematics and a Revised Taxonomy of the Onocleoid Ferns (Dryopteridaceae: Onocleeae). American Journal of Botany, 84(6): 840–849. Jacke, D., and Toensmeier, E. 2008. Edible Forest Gardens. Ecological Design and Practice for Temperate-Climate Permaculture. Hartford, VT: Chelsea Green Publishing. FNAEC (Flora of North America Editorial Committee), editor. 1993. Flora of North America, north of Mexico. Volume 2: Pteridophytes and Gymnosperms. New York: Oxford University Press. Maiz-Tome, L. 2016. Onoclea sensibilis. The IUCN Red List of Threatened Species. <a>http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T64319082A67730257.en</a>. MBG (Missouri Botanical Garden), Onoclea sensibilis. Plant Finder. [accessed 2019 Jun 12]. <a>www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=l300</a> Wu, Z. Y., Raven, P. H., and Hong, D. Y., eds. 2013. Flora of China. Vol. 2-3 (Lycopodiaceae through Polypodiaceae). Beijing: Science Press, and St. Louis: Missouri Botanical Garden Press.

Description

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