Polystichum kruckebergiiW.H.Wagner

Kruckeberg's hollyfern

WFO wfo-0001109270 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Polystichum kruckebergii, photographed by John Brew
fig. a John Brew, CC BY 4.0 / 2020-09-04 / obs. 97506678

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
The New York Botanical Garden
Accession
991110
Filed as
Polystichum kruckebergii W.H.Wagner
Det. by
W. H. Wagner 1966-01-01
Collected
C. G. Pringle 1881-08-19
Origin
US
The sheet
View the digitised specimen (CC BY 4.0)

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.

Native range 9 botanical countries

Regions where Polystichum kruckebergii is native: Alaska, British Columbia, California, Idaho, Montana, Nevada, Oregon, Utah, Washington AlaskaBritish ColumbiaCaliforniaIdahoMontanaNevadaOregonUtahWashington
Native distribution of Polystichum kruckebergii, 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.
RegionTDWG codeContinent
Alaska ASK NORTHERN AMERICA
British Columbia BRC
California CAL
Idaho IDA
Montana MNT
Nevada NEV
Oregon ORE
Utah UTA
Washington WAS

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 178 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -16.2 °C -10.3 °C -4.6 °C
Warmest month, mean daily high 14.8 °C 16.8 °C 25.4 °C
Annual rainfall 827 mm 1,317 mm 3,998 mm
Rainfall in the driest quarter 94 mm 163 mm 544 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 178 research-grade observations of Polystichum kruckebergii 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.

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. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. 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.