Claytosmunda claytoniana(L.) Metzgar & Rouhan

interrupted fern

WFO wfo-1000067200 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Claytosmunda claytoniana, photographed by Lynn Harper
fig. a Lynn Harper, CC0 1.0 / 2022-06-13 / obs. 205879284
Claytosmunda claytoniana, photographed by Larry Jensen
fig. b Larry Jensen, CC BY 4.0 / obs. 205554633
Claytosmunda claytoniana, photographed by Ryan Sorrells
fig. c Ryan Sorrells, CC BY 4.0 / obs. 205636030
Claytosmunda claytoniana, photographed by Sandra Keller
fig. d Sandra Keller, CC BY 4.0 / obs. 205174718
Claytosmunda claytoniana, photographed by Benoit Renaud
fig. e Benoit Renaud, CC BY 4.0 / obs. 205235414
Claytosmunda claytoniana, photographed by Craig Martin
fig. f Craig Martin, CC0 1.0 / obs. 204244215
Claytosmunda claytoniana, photographed by Matt Pelikan
fig. g Matt Pelikan, CC BY 4.0 / obs. 204234319
Claytosmunda claytoniana, photographed by Lynn Harper
fig. h Lynn Harper, CC0 1.0 / obs. 203971533

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

The specimen a real sheet, in a real collection

Herbarium
Smithsonian, US National Herbarium
Accession
US 3527048
Filed as
Claytosmunda claytoniana (L.) Metzgar & Rouhan
Det. by
Testo, W.
Collected
Tibet-MacArthur, J. Wen, Z. Nie, R. J. Soreng, K. Rankin, L. Yue, M. Wang & X. Yue 2007-07-22
Origin
CN
The sheet
View the digitised specimen (CC0 1.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Confused with by our own model

These are not lookalikes we guessed at. Each one is a species our identification model genuinely mistook for this plant, and how many times. The error rate is published.

Native range 50 botanical countries

Regions where Claytosmunda claytoniana is native: China South-Central, China Southeast, Japan, Manchuria, Primorye, Taiwan, Tibet, Assam, East Himalaya, Nepal, Pakistan, West Himalaya, Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Georgia, Illinois, Indiana, Iowa, Kentucky, Labrador, Maine, Manitoba, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Brunswick, New Hampshire, New Jersey, New York, Newfoundland, North Carolina, Nova Scotia, Ohio, Ontario, Pennsylvania, Prince Edward I., Québec, Rhode I., South Carolina, Tennessee, Vermont, Virginia, West Virginia, Wisconsin China South-CentralChina SoutheastJapanManchuriaPrimoryeTaiwanTibetAssamEast HimalayaNepalPakistanWest HimalayaAlabamaArkansasConnecticutGeorgiaIllinoisIndianaIowaKentuckyLabradorMaineManitobaMarylandMassachusettsMichiganMinnesotaMississippiMissouriNew BrunswickNew HampshireNew JerseyNew YorkNewfoundlandNorth CarolinaNova ScotiaOhioOntarioPennsylvaniaPrince Edward I.QuébecSouth CarolinaTennesseeVermontVirginiaWest VirginiaWisconsin DelawareDistrict of ColumbiaRhode I.
Native distribution of Claytosmunda claytoniana, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Alabama ALA NORTHERN AMERICA
Arkansas ARK
Connecticut CNT
Delaware DEL
District of Columbia WDC
Georgia GEO
Illinois ILL
Indiana INI
Iowa IOW
Kentucky KTY
Labrador LAB
Maine MAI
Manitoba MAN
Maryland MRY
Massachusetts MAS
Michigan MIC
Minnesota MIN
Mississippi MSI
Missouri MSO
New Brunswick NBR
New Hampshire NWH
New Jersey NWJ
New York NWY
Newfoundland NFL
North Carolina NCA
Nova Scotia NSC
Ohio OHI
Ontario ONT
Pennsylvania PEN
Prince Edward I. PEI
Québec QUE
Rhode I. RHO
South Carolina SCA
Tennessee TEN
Vermont VER
Virginia VRG
West Virginia WVA
Wisconsin WIS
China South-Central CHC ASIA-TEMPERATE
China Southeast CHS
Japan JAP
Manchuria CHM
Primorye PRM
Taiwan TAI
Tibet CHT
Assam ASS ASIA-TROPICAL
East Himalaya EHM
Nepal NEP
Pakistan PAK
West Himalaya WHM

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Where it actually grows measured, from 116 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -17.4 °C -10.6 °C 0.6 °C
Warmest month, mean daily high 16.4 °C 23.7 °C 27.2 °C
Annual rainfall 939 mm 1,297 mm 4,876 mm
Rainfall in the driest quarter 143 mm 270 mm 347 mm

It is found where winters are severely cold. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 116 research-grade observations of Claytosmunda claytoniana that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.

Also published as 23 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Osmunda basilaris Spreng.
  • Osmunda claytoniana L.
  • Osmunda claytoniana f. dubia (Grout) Clute
  • Osmunda claytoniana f. tomentosa Neidorf
  • Osmunda claytoniana subsp. pilosa (Wall. ex Grev. & Hook.) Fraser-Jenk.
  • Osmunda claytoniana subsp. vestita (Milde) Á.Löve & D.Löve
  • Osmunda claytoniana var. dubia Grout
  • Osmunda claytoniana var. pilosa (Wall. ex Hook. & Grev.) Ching
  • Osmunda claytoniana var. vestita Milde
  • Osmunda interrupta Michx.
  • Osmunda monticola Wall.
  • Osmunda monticola var. vestita Wall.
  • Osmunda pilosa Wall. ex Grev. & Hook.
  • Osmundastrum claytonianum (L.) Tagawa
  • Osmundastrum claytonianum subsp. pilosum (Wall. ex Hook. & Grev.) Tzvelev
  • Osmundastrum claytonianum var. pilosum (Wall. ex Hook. & Grev.) W.M.Chu & S.G.Lu
  • Osmundastrum claytonianum var. vestitum (Milde) Tagawa
  • Osmundastrum pilosum (Wall. ex Grev. & Hook.) Shmakov
  • Plenasium claytonianum (L.) C.Presl
  • Plenasium interruptum C.Presl
  • Plenasium pilosum (Wall. ex Hook. & Grev.) C.Presl
  • Plenasium pilosum (Wall. ex Grev. & Hook.) C.Presl
  • Struthiopteris claytoniana (L.) Bernh.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. USDA PLANTS Database. common name, checklist symbol OSCL2. public domain. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.