Epilobium hornemanniiRchb.

Hornemann's willowherb

WFO wfo-0000669212 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 8 separate observations

Epilobium hornemannii, photographed by Jens-Christian Svenning
fig. a Jens-Christian Svenning, CC BY 4.0 / 2021-07-25 / obs. 146168826
Epilobium hornemannii, photographed by Jens-Christian Svenning
fig. b Jens-Christian Svenning, CC BY 4.0 / obs. 145226652
Epilobium hornemannii, photographed by Jens-Christian Svenning
fig. c Jens-Christian Svenning, CC BY 4.0 / obs. 144962648
Epilobium hornemannii, photographed by Spencer Quayle
fig. d Spencer Quayle, CC0 1.0 / obs. 138772997
Epilobium hornemannii, photographed by Dag Endresen
fig. e Dag Endresen, CC0 1.0 / obs. 88182654
Epilobium hornemannii, photographed by Alison Northup
fig. f Alison Northup, CC BY 4.0 / obs. 50196280
Epilobium hornemannii, photographed by naokitakebayashi
fig. g naokitakebayashi, CC BY-SA 4.0 / obs. 44889419
Epilobium hornemannii, photographed by Doug Weihrauch
fig. h Doug Weihrauch, CC BY 4.0 / obs. 24996322

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.

Native range 40 botanical countries

Regions where Epilobium hornemannii is native: Japan, Kamchatka, Khabarovsk, Kuril Is., Magadan, Sakhalin, Yakutiya, East European Russia, Finland, Iceland, North European Russia, Norway, Sweden, Alaska, Alberta, Aleutian Is., Arizona, British Columbia, California, Colorado, Greenland, Idaho, Maine, Montana, Nevada, New Brunswick, New Hampshire, New Mexico, New York, Newfoundland, Northwest Territories, Nova Scotia, Ontario, Oregon, Québec, South Dakota, Utah, Washington, Wyoming, Yukon JapanKamchatkaKhabarovskMagadanSakhalinYakutiyaEast European RussiaFinlandIcelandNorth European RussiaNorwaySwedenAlaskaAlbertaArizonaBritish ColumbiaCaliforniaColoradoGreenlandIdahoMaineMontanaNevadaNew BrunswickNew HampshireNew MexicoNew YorkNewfoundlandNorthwest TerritoriesNova ScotiaOntarioOregonQuébecSouth DakotaUtahWashingtonWyomingYukon
Native distribution of Epilobium hornemannii, 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
Alberta ABT
Aleutian Is. ALU
Arizona ARI
British Columbia BRC
California CAL
Colorado COL
Greenland GNL
Idaho IDA
Maine MAI
Montana MNT
Nevada NEV
New Brunswick NBR
New Hampshire NWH
New Mexico NWM
New York NWY
Newfoundland NFL
Northwest Territories NWT
Nova Scotia NSC
Ontario ONT
Oregon ORE
Québec QUE
South Dakota SDA
Utah UTA
Washington WAS
Wyoming WYO
Yukon YUK
Japan JAP ASIA-TEMPERATE
Kamchatka KAM
Khabarovsk KHA
Kuril Is. KUR
Magadan MAG
Sakhalin SAK
Yakutiya YAK
East European Russia RUE EUROPE
Finland FIN
Iceland ICE
North European Russia RUN
Norway NOR
Sweden SWE

Not drawn on the map: Kuril Is., Aleutian Is.. We hold no public-domain boundary for these regions, so they are listed rather than guessed at.

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 117 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -23.9 °C -15.8 °C -3.6 °C
Warmest month, mean daily high 11.6 °C 16.3 °C 23.3 °C
Annual rainfall 489 mm 1,153 mm 3,328 mm
Rainfall in the driest quarter 61 mm 171 mm 437 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 117 research-grade observations of Epilobium hornemannii 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.

  • Epilobium alpinum var. behringianum (Hausskn.) S.L.Welsh
  • Epilobium alpinum var. nutans Hornem.
  • Epilobium alpinum var. sertulatum (Hausskn.) S.L.Welsh
  • Epilobium alsinifolium Blytt
  • Epilobium alsinifolium var. hornemannii Lange
  • Epilobium behringianum Hausskn.
  • Epilobium bongardii Hausskn.
  • Epilobium bongardii f. minus Hausskn.
  • Epilobium bongardii f. umbrosum Hausskn.
  • Epilobium cupreum Lange
  • Epilobium foucaudianum H.Lév.
  • Epilobium glaucinum Hausskn.
  • Epilobium hornemannii f. albiflorum Moldenke
  • Epilobium hornemannii f. album Moldenke
  • Epilobium hornemannii var. foucaudianum (H.Lév.) H.Hara
  • Epilobium lucens H.Lév.
  • Epilobium nutans Hornem.
  • Epilobium origanifolium Andersson
  • Epilobium roseum Turcz.
  • Epilobium roseum Turcz. ex Ledeb.
  • Epilobium sertulatum Hausskn.
  • Epilobium steckerianum Fernald
  • Epilobium uralense Rupr.

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.