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Wisconsin Plant of the Week

Onoclea sensibilis L.

Dryopteridaceae (Wood Fern Family)

Common Name:

sensitive fern

11/22/1999

Sensitive fern is a native fern that grows in marshes, boggy woods and borders of shaded ponds.   It's perennial, usually in neutral to slightly acid soil, and spreads by long-creeping branched rhizomes.

Like many ferns the leaves of sensitive fern are dimorphic -- the fertile (spore bearing) and sterile fronds look very different.  The sterile or vegetative fronds are the first to grow in spring.  They grow to 1 m tall and are yellow-green, triangular shaped and pinnately divided into 8 to 12 paired segments.  The individual segments of the frond have wavy margins and the central stalk, or rachis, is winged.   The sterile fronds are deciduous, turning golden yellow with the first frost -- the origin of the common name.

Fertile leaves are shorter, appear by mid-summer and are brown to black and leathery when mature. The margins of the fronds are inrolled and contain clusters of spore cases. The fertile fronds persist at least through one winter, and release green spores in the spring.

  • Origin of the name: Onoclea: Gr., onos, vessel; kleiein. to close; refers to the cluster of spore cases concealed by the fronds
    sensibilis: L. pp. sentire, to feel
  • RangeEastern N. America and E. Asia
  • WI Range:  Statewide
  • Common associates:  Bluejoint grass, water hemlock, elms, green ash
  • Wetland Indicator Status: FACW
  • Coefficient of Conservatism:  C = 8 (S&W) C = 2 (MI)
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