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Interrupted fern

Osmunda claytoniana (accepted: Claytosmunda claytoniana) · Osmundaceae

Your local evidence lens

Separate evidence questions, never one approval badge

Set a ZIP to compare this record with state distribution, native range, USDA hardiness, and invasive records.

A genus split is not a placement verdict. Set a ZIP to read the local documented split.

1. Fire evidence and conditions

Fire evidence: Fire-resistant — location does not change the cited classification.
Fire-performance conditions: 1 condition stated in cited fire-evidence rows.
Fire ecology context: No section-reviewed fire-ecology context is normalized.
Placement evidence: 0 source placement records; source schemes remain separate.
Evidence regions: Global; north-eastern and mid-Atlantic United States
Maintenance: No sourced horticultural maintenance assertion is normalized; fire-test conditions do not supply maintenance advice.

Typed publication scope: 1 scope across 1 cited fire source

Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter · Official scoped edition
- Northeastern and mid-Atlantic study sites (ME, MD, MA, NY, VA footprint); partial normalized coverage · 2007-08-20
  The authors collected foliage and twigs across study sites in Maine, Maryland, Massachusetts, New York, and Virginia, then conditioned and tested the samples in a cone calorimeter. FireApproved publishes 37 exact source owners only as multi-state laboratory context. The source does not establish that every taxon was sampled in every named state, whole-plant behavior, landscape suitability, or state planting guidance.

2. Why this plant is relevant here

State distribution: Documented in AL, AR, CT, DC, DE, GA, IA, IL, IN, KY, MA, MD, ME, MI, MN, MO, MS, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WI, WV.
Native range: No current cited or legacy state native range is normalized.
Introduced / established: No introduced or established row is normalized; that does not prove native status.
USDA hardiness: Documented minimum 3a; no upper limit is documented.

3. Legal, ecological, and broader status

Legal-list status: Set a location for an exact legal-list result; source silence is not clearance.
Seed-list status: Set a location to compare the separate state noxious-weed seed layer.
Reported invasive here: No ecological invasive report is normalized; that does not prove noninvasiveness.
Broader regional context: Aggregate AK, HI, and L48 evidence is shown only as regional context, never as an exact-state finding.
Federal context: Federal designations remain separate from state legal-list results.

How to read this page

The status above is computed from the cited rows below: independent recommendations can support a fire-resistant result, an avoid row can produce keep-away, and disagreement stays visible as conflict. Placement notes preserve each source’s own scheme rather than translating unlike rules into one scale. This is evidence about a plant, not permission to plant it in every part of the defensible space; Zone 0 remains noncombustible.

Interrupted fern (Osmunda claytoniana) — Photo: (c) Marilyne Busque-Dubois, some rights reserved (CC BY), uploaded by Marilyne Busque-Dubois (CC BY), via iNaturalist. Species-typical, not necessarily this cultivar.

Form: perennial
USDA hardiness: Minimum 3a; upper limit not documented
Mature height: ~4 ft
Water need: high
Grows in: AL, AR, CT, DC, DE, GA, IA, IL +22
Rated in: Global; north-eastern and mid-Atlantic United States
Family: Osmundaceae
Evidence: 2 cited sources

Plant hardiness evidence

These values describe the plant source. Your ZIP zone comes from the separate 2023 USDA Plant Hardiness Zone Map. Whole-zone values stay whole-zone, and a single unresolved value is not treated as a tolerance range. Different source boundaries stay separate: overlapping statements are compared independently, while only ranges with no shared zone are called a conflict.

USDA PLANTS Database — Plant Characteristics · record OSCL2 · PLANTS Help Document 2022; characteristics cache retrieved 2026-08-23 · as of 2026-08-26

Minimum 3a · no upper limit documented · half zone precision · derived containing band

Exact source measurement: -38°F; mapped only to its containing half-zone.

Source taxon: Osmunda claytoniana · source identifier match.

Source location: PlantCharacteristics record 14166, Temperature, Minimum (°F).

Conditions in the fire evidence

These describe tested or rated plant material. They are not horticultural maintenance instructions.

cured: Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter evidence row

The evidence

Grouped by what each source concluded. Primary evidence rated the plant itself (a lab, field program, or original curation); corroboration compiled or republished another source's rating and resolves to its root lineage.

Listed without a rating (1)

FLAMITS: FLAMmability plant traiTS database — Dryad / Global Ecology and Biogeography · Dryad version 9 · original source Corroboration Trait database lineage: meta-aggregator

“calorific value (kcal/kg): 2985.57” · score 2985.57 (FLAMITS — calorific value (kcal/kg))

FLAMITS record 2878; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site Dibble2007-1; sampling ND. Primary study Dibble2007: Dibble, A. C., White, R. H., & Lebow, P. K. (2007). Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter: invasive versus non-invasive plants. International journal of wildland fire, 16, 426-443.

Last verified 2026-08-24. JSON (CC BY 4.0)

Profiles: USDA PLANTS · GBIF ·

Osmunda claytoniana (Interrupted fern). FireApproved. https://fireapproved.com/plants/claytosmunda-claytoniana/. Last verified 2026-08-24.