Epilobium cinereum
Common names
willowherb
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified description
An erect much branched perennial plant, often with an overall reddish look. Leaves fairly small, grey-green to reddish, narrow elliptic, and covered in strigulose hair, with prominent and widely spaced teeth. Flowers very rarely white, often rose tinted, on a strigulose hairy ovary and pedicel.
Flower colours
Red/Pink
Detailed description
Erect, much branched perennial or annual herb 0.15-0.60 m tall, often reddish-tinged, not obviously stoloniferous; plants strigulose, inflorescence, densely so, hairs comprising an admixture of glandular or non-glandular erect hairs often also present, the stems pubescent all round, conspicuously exfoliating and often somewhat woody near the base. Leaves mostly opposite alternate alternate in the upper half, grey-green, often tinged reddish, densely strigulose, the lateral veins visible to prominent, usually 3-5 on each side of the midrib; lamina 5.0-23.0 × 1.5-7.0 mm, linear to narrowly elliptic, apex subacute to acute or obtuse, base attenuate, margins coarsely serrate, bearing 1-8 teeth on each side, shortly pedunculate or subsessile. Inflorescence erect. Flowers erect. Ovary 10-24 mm long, on a pedicel 0-15 mm long, investiture usually densely though finely strigulose with an admixture of white or greyish-white, glandular or eglandular erect hairs. Floral tube 0.6-1.2 mm deep, 1.2-1.9 mm diameter, usually bearing a conspicuous ring of long hairs within. Sepals 2.5-7.5 × 0.8-1.7 mm, keeled, strigulose, bearing glandular or eglandular hairs also. Petals 3.5-12.0 × 2.0-6.5 mm, the notch 0.8-1.5 mm deep, rose-purple (very rarely white). Stamen filaments white of two types: long 1.5-5.0 mm long and short 1.0-4.5 mm. Anthers cream, 0.5-1.0 × 0.3-0.52 mm. Style 2.5-9.0 mm long, white. Stigma 1.5-4.0 × 0.9-1.5 mm, white, clavate, surrounded by (very rarely held well above) the anthers at anthesis. Capsule 30-68 mm long, densely strigulose, indumentum comprising an admixture of glandular and eglandular erect hairs; pedicel 6-20 mm long. Seeds 0.8-1.0 × 0.3-0.4 mm, brown, reticulate-mammilate to reticulate-papillose, obovoid, chalazal callus absent, apex rounded (not beaked); coma 7.0-10.5 mm long, white, breaking off readily.
Similar taxa
Epilobium cinereum is easily distinguished from all other epilobia except the threatened E. hirtigerum on account of its upright, heavily branched growth habit, finely puberulent, greyish (often red-tinged) stems, foliage, pedicels and capsules, and dark rose-purple flowers which open widely at anthesis. Epilobium hirtigerum is usuall;y easily distinguished from E. cinereum on account of its larger overall size, glabrous stoloniferous winter growth habit, and by the stem hairs which in E. hirtigerum are in mixtures of long, spreading eglandular, shorter glandular and strigulose hairs. In the North Island at least, E. hirtigerum is further distinguished by its smaller, consistently white flowers which scarcely open.
Distribution
Indigenous. New Zealand: North, South, Stewart and Chatham Islands. Also Australia (Queensland, New South Wales, Victoria, South Australia and Tasmania). Naturalised at least on the Hawaiian Islands if not elsewhere in the Pacific.
Habitat
Coastal to upper montane. In open, often dryer habitats on banks and rock outcrops, as well as around lake, river and ephemeral wetland margins. Often a prominent urban weed, especially in derelict properties, old car yards, and in car parks. In these habitats it often associates with Epilobium ciliatum, E. hirtigerum, E. tetragonum and Lachnagrostis filiformis.
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2023 | Not Threatened | Qualifiers: SO
Detailed taxonomy
Genus
Family
Synonyms
Epilobium billardiereanum subsp. cinereum (A.Rich.) P.H.Raven et Engelhorn
Taxonomic notes
Raven & Raven (1976) prefer to treat Epilobium cinereum as E. billardierianum subsp. cinereum. However, irrespective of their comments for Australia it is clear that in New Zealand E. cinereum is a widespread, morphologically stable unit that is only occasionally seen sympatric (and even syntopic) with the ecologically and morphologically distinct E. billardierianum. Further hybrids between both subspecies and E. billardierianum are as yet unknown from New Zealand, although Raven & Raven (1976) suggest that they are frequent in Australia. From a New Zealand perspective it is difficult to accept such morphologically distinct species as subspecies because of their reported behavior in Australia. Also, as with any Epilobium, given an opportunity hybridism is likely to happen, even with distinct relatives, as it is the main driver for speciation in the Australasian representatives of the genus. in this regard Raven & Raven (1976) are inconsistent, accepted at species rank other epilobia, which following their treatment of E. billardierianum should also be regarded as subspecies, or even merged.
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
September - May
Fruiting
October - July
Propagation technique
Very weedy and probably best not cultivated as it is inclined to spread rapidly. Epilobium cinereum is a common urban weed in many cities and towns of eastern New Zealand
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
UPL: Obligate Upland
Rarely is a hydrophyte, almost always in uplands (non-wetlands).
Other information
Etymology
epilobium: From the Greek epi- ‘upon’ and lobos ‘a pod’, the flowers appearing to be growing on the seed pod.
cinereum: Ash-grey
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
EPIBSC
Chromosome number
2n = 36
Previous conservation statuses
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2022-2023 using the New Zealand Threat Classification System (NZTCS) – more information about this can be found on the NZTCS website. This report includes replaces all previous NZTCS lists for vascular plants. Previous assessments can be found here.
- Conservation status of vascular plants in Aotearoa New Zealand, 2023. 2024. Peter J. de Lange, Jane Gosden, Shannel P. Courtney, Alexander J. Fergus, John W. Barkla, Sarah M. Beadel, Paul D. Champion, Rowan Hindmarsh-Walls, Troy Makan and Pascale Michel Department of Conservation. Source: NZTCS and licensed by DOC for reuse under the Creative Commons Attribution 4.0 International licence.
2017 | Not Threatened | Qualifiers: SO
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
Otago: 2024 | Regionally Not Threatened
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Otago conservation status information is sourced from the “Regional conservation status of indigenous vascular plants in Otago” Jarvie S et al. (2024) report.
Auckland: 2025 | Regionally Not Threatened | Qualifiers: DPS, DPT
The regional threat classification system leverages off the national assessments in the NZTCS, providing information relevant for the regional context. Auckland conservation status information is sourced from the “Conservation status of vascular plant species in Tāmaki Makaurau / Auckland” Simpkins E et al. (2025) report.
Referencing and citations
References and further reading
Raven, P.H.; Raven, T.E. 1976: The genus Epilobium in Australasia. New Zealand DSIR Bulletin 216. Wellington, Government Printer.
Webb, C.J.; Simpson, M.J.A. 2001: Seeds of New Zealand Gymnosperms and Dicotyledons. Christchurch, Manuka Press.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 22 August 2011. Description adapted from Raven & Raven (1976) and Webb & Simpson (2001).