Specimen record
Sensitive Fern
Onoclea sensibilis
Description
Named for its sensitivity to frost — it is one of the first ferns to be killed by autumn's cold — sensitive fern is a common wetland species with an unusual appearance for a fern. Its broad, once-pinnate fronds with net-like venation look more like a coarsely lobed leaf than a typical fern frond. The separate fertile fronds are striking: stiff, dark brown stalks bearing bead-like clusters of sporangia that persist upright through winter.
Identification tips
- 1Broad, coarsely lobed fronds with net-like (reticulate) venation — atypical for ferns
- 2Pinnae with wavy, undulating margins, not individually separated to the rachis
- 3Separate bead-like fertile fronds — stiff, dark brown, persistent through winter
- 4Very sensitive to frost — among the first ferns to die back in autumn
- 5Grows in wet, open habitats — pond edges, ditches, wet meadows
Specimen & preservation notes
Press a vegetative frond showing the net-like venation (unusual for ferns — highlight on the label). Collect a bead-like fertile frond separately — they press flat and are excellent diagnostic specimens. Both types can be mounted on a single herbarium sheet for comparison.
Habitats
Collection calendar
| Wk | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov |
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| 4 |
Collection notes
Season check
No flowering records for this species yet.
Flowering records: 0 iNaturalist observations, Massachusetts · Nearby: 1531 observations within 25 km