Epilobium obscurumSchreb.

dwarf willowherbshort-fruited willowherb

WFO wfo-0000669496 Accepted WFO 2026-06 8 photographs CC0 / CC BY / CC BY-SA

Plate 1 figs. a–h · 6 observations

This species has been photographed under an open licence only 6 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.

Epilobium obscurum, photographed by Stephen James McWilliam
fig. a Stephen James McWilliam, CC0 1.0 / 2021-08-28 / obs. 154504747

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 293065
Filed as
Epilobium obscurum Schreb.
Det. by
not recorded on this sheet
Collected
J. Ball 1848-08
Origin
AU
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.

Native range 38 botanical countries

Regions where Epilobium obscurum is native: Algeria, Azores, Canary Is., Madeira, Morocco, East Aegean Is., Türkiye, Albania, Austria, Baltic States, Belarus, Belgium, Bulgaria, Central European Russia, Corse, Czechia-Slovakia, Denmark, East European Russia, Finland, France, Germany, Great Britain, Greece, Hungary, Ireland, Italy, Netherlands, North European Russia, Northwest European Russia, Norway, NW. Balkan Pen., Poland, Romania, Sardegna, Spain, Sweden, Switzerland, Ukraine AlgeriaMoroccoEast Aegean Is.TürkiyeAlbaniaAustriaBaltic StatesBelarusBelgiumBulgariaCentral European RussiaCorseCzechia-SlovakiaDenmarkEast European RussiaFinlandFranceGermanyGreeceHungaryIrelandItalyNetherlandsNorth European RussiaNorthwest European RussiaNorwayNW. Balkan Pen.PolandRomaniaSpainSwedenSwitzerlandUkraine AzoresCanary Is.MadeiraSardegna
Native distribution of Epilobium obscurum, 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
Albania ALB EUROPE
Austria AUT
Baltic States BLT
Belarus BLR
Belgium BGM
Bulgaria BUL
Central European Russia RUC
Corse COR
Czechia-Slovakia CZE
Denmark DEN
East European Russia RUE
Finland FIN
France FRA
Germany GER
Great Britain GRB
Greece GRC
Hungary HUN
Ireland IRE
Italy ITA
Netherlands NET
North European Russia RUN
Northwest European Russia RUW
Norway NOR
NW. Balkan Pen. YUG
Poland POL
Romania ROM
Sardegna SAR
Spain SPA
Sweden SWE
Switzerland SWI
Ukraine UKR
Algeria ALG AFRICA
Azores AZO
Canary Is. CNY
Madeira MDR
Morocco MOR
East Aegean Is. EAI ASIA-TEMPERATE
Türkiye TUR

Not drawn on the map: Great Britain. We hold no public-domain boundary for this region, so it is 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.

Flowering 37 in flower of 43 examined

Proportion of examined Epilobium obscurum in flower, by month
Month In flower Examined Share 95% interval
Jan 1 1 too few examined
Feb 4 5 80% 38% to 96%
Mar 1 1 too few examined
Apr 0 3 too few examined
May 0 0 too few examined
Jun 5 5 100% 57% to 100%
Jul 6 6 100% 61% to 100%
Aug 5 6 83% 44% to 97%
Sep 2 2 too few examined
Oct 5 6 83% 44% to 97%
Nov 6 6 100% 61% to 100%
Dec 2 2 too few examined

Peak flowering in Jun. Each bar is the share of Epilobium obscurum observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 37 of 43 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 6 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 205 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -5.7 °C 3.6 °C 12.8 °C
Warmest month, mean daily high 17.8 °C 21.8 °C 26.6 °C
Annual rainfall 652 mm 1,139 mm 1,743 mm
Rainfall in the driest quarter 89 mm 174 mm 270 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 205 research-grade observations of Epilobium obscurum 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. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 40 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.

  • Chamaenerion obscurum Schreb.
  • Chamaenerion obscurum (Schreb.) Ehrh.
  • Chamaenerion ramosissimum Moench
  • Epilobium ambiguum Fr.
  • Epilobium anagallidifolium var. diffusum Samp.
  • Epilobium chordorrhizum Fr.
  • Epilobium decumbens Dumort.
  • Epilobium erectum Petrie
  • Epilobium fennicum Laest. ex Hausskn.
  • Epilobium foliosum Dörfl.
  • Epilobium gemmascens Lange
  • Epilobium gemmiferum Willk. & Lange
  • Epilobium gillotii H.Lév.
  • Epilobium junceum subsp. macrophyllum Hausskn.
  • Epilobium madeirense Hausskn.
  • Epilobium miguelense H.Lév.
  • Epilobium obscurum Rchb.
  • Epilobium obscurum f. crassicaule E.S.Marshall
  • Epilobium obscurum subsp. virgatum (Lam.) Nyman
  • Epilobium obscurum var. foliosum Ficinus
  • Epilobium obscurum var. herminicum Samp.
  • Epilobium obscurum var. molleri H.Lév.
  • Epilobium obscurum var. pseudopalustre P.Monts.
  • Epilobium palustre var. virgatum (Lam.) Hartm.

and 16 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.
  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.