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Sterile Fronds


Close up of leaflets

Onoclea sensibilis

Common Name: Sensitive Fern
Family: Dryopteridaceae


Description:  This fern species is one of the first species to begin growing in wetlands after flooding or a natural disturbance. It can be identified by the wavy leaflets on the sterile fronds and by the brown spikes of the fertile fronds.
Leaves:
 The sterile fronds are light green in color and grow to up 3 feet tall. On each frond there are up to 12 opposite paired leaflets that have wavy edges and netlike veins. The fertile fronds are 1 foot long with dark brown spike of hard spherical spores. They appear July to August and persist through the winter.
Seeds:
 The sori located on the fertile ferns are round and covered by a hard dry outer shell.
Stem: The stems of the fronds are robust and erect.
Branching Pattern:
  palmate
Height: up to 3 feet tall
Conditions/Habitat/Kind of Forest:  They can be found in wet meadows, wooded swamps and along road sides. They are tolerant of sun and shade and can grow in slightly acidic soil requires. However, they need wet or moist soil to survive.
Known Wildlife Interactions: When growing in dense groups they serve as a hiding place for small animals and the fertile fronds serve as food throughout the winter for birds and animals.
Range:  It is found in North America east of the Rocky Mountains to the Atlantic Coast. It is also found in Asia
Conservation Status-US/ World Wide: Not threatened in the U.S. or globally.
Uses (Human): None known

References:

Connecticut Wildflowers.  March 30, 2006.  Connecticut Botanical Society.  Accessed:  January 20, 2006. <http://www.ct-botanical-society.org/galleries/polygonumsagi.html>

Plants for a Future.  June 2004.  Accessed: March 30, 2006.  <http://www.pfaf.org/database/plants.php?Polygonum+sagittatum>

The Pennsylvania Flora Project.  Botany Department, Morris Arboretum of the University of Pennsylvania.  Accessed:  March 30, 2006. <http://www.paflora.org>

 IUCN Red List of Threatened Species <http://www.iucnredlist.org>

Chadde, Steve W. A Great Lakes Wetland Flora. Pocketflora Press. 2002. pg.50

Redington, Charles B. Plants in Wetlands. Redington Field Guides.1994. pg. 260

This page was created by: A. Coiro, Muhlenberg College
Photos by: L. Rosenberg, edited by N. Smith
Last updated 04/25/06