Polytrichum longisetumSw. ex Brid.

polytrichum mossslender haircap

WFO wfo-0001170151 Accepted WFO 2026-06 8 photographs CC0

Plate 1 figs. a–h · 2 observations

This species has been photographed under an open licence only 2 times, so some figures below are different views of the same plant, taken on the same day, rather than different individuals. They are usually different parts of it: the leaf, the flower, the bark.

Polytrichum longisetum, photographed by Randal
fig. a Randal, CC0 1.0 / 2022-05-16 / obs. 198288638

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.

Where it actually grows measured, from 35 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -13.3 °C -4.4 °C 0.6 °C
Warmest month, mean daily high 16.3 °C 21.9 °C 25.8 °C
Annual rainfall 677 mm 890 mm 2,698 mm
Rainfall in the driest quarter 108 mm 173 mm 354 mm

It is found where winters bring hard frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 35 research-grade observations of Polytrichum longisetum 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 Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one.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 44 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.

  • Atrichum anomalum Milde
  • Catharinea dixonii Braithw.
  • Catharinea spinosa Warnst.
  • Catharinella dixonii (Braithw.) Kindb.
  • Oligotrichum sibiricum Bard.
  • Pogonatum urnigerum var. nigrescens (DC.) Brid.
  • Polytrichastrum longisetum (Sw. ex Brid.) G.L.Sm.
  • Polytrichastrum longisetum f. anomalum (Milde) Schljakov
  • Polytrichastrum longisetum var. anomalum (Milde) Ignatov & G.L.Merr.
  • Polytrichum anomalum (Milde) Milde
  • Polytrichum attenuatum var. aurantiacum (Hoppe ex Brid.) Turner
  • Polytrichum aurantiacum Hoppe ex Brid.
  • Polytrichum commune var. aurantiacum (Hoppe ex Brid.) Wahlenb.
  • Polytrichum formosum var. aurantiacum (Hoppe ex Brid.) Hartm.
  • Polytrichum formosum var. gracile (Menzies) Venturi & Bott.
  • Polytrichum gracile Menzies
  • Polytrichum gracile f. alpestre Podp.
  • Polytrichum gracile f. anomalum (Milde) Osada
  • Polytrichum gracile f. aquaticum (Bryhn) Mönk.
  • Polytrichum gracile f. atromitrium (Meyl.) Podp.
  • Polytrichum gracile f. brevisetum Warnst.
  • Polytrichum gracile f. fasciculatum (Warnst.) Podp.
  • Polytrichum gracile f. juvenile Podp.
  • Polytrichum gracile f. majus Katić

and 20 more.

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.

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. It has no native range either: Kew's checklist does not cover this taxon.