Epilobium billardiereanum
Common names
willowherb
Biostatus
Native
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified description
A distinctly coastal species, generally found in sandy ground, with a decumbent habit, narrow ovate to ovate leaves with fine teeth, and flowering stems erect with a dense covering of white grey striglose hairs on the upper stems, pedicels, capsule ansd sepals.
Flower colours
White
Detailed description
Decumbent, prostrate, widely spreading, sparingly to well-branched perennial herb forming rather open, ± circular patches up to 1 m diameter, and up to 0.95 m tall (where plants have pushed up through surrounding vegetation), with flowering branches ± weakly ascendent. Branch stems ± glabrescent to weakly strigulose, branch bases ± woody, and often conspicuously exfoliating in well established specimens. Leaves mostly opposite alternate in and near the inflorescence, or alternate in the upper half, subsessile, yellow-green, green, often red-tinged, glabrous and shining the lateral veins visible to prominent, usually 3–5 on each side of the midrib; lamina 5.0–40.0 × 6.0–20.0 mm, narrowly ovate to ovate, base rounded to truncate, apex obtuse, margins densely and evenly serrulate, bearing 16–40 teeth on each side. Inflorescence on ascending branches, ± erect, densely grey-strigulose with glandular and eglandular hairs absent. Flowers erect. Ovaries densely grey-strigulose erect hairs, 10–30 mm long, on a pedicel 2–16 mm long. Floral tube 0.6–2.1 mm deep, 1.4–2.8 mm diameter, often bearing a conspicuous ring of long hairs within. Sepals 2.5–7.8 × 0.9–2.1 mm, keeled, strigulose. Petals 3.7–7.0 × 3.0–5.0 mm, the notch 1.0–1.8 mm deep, white flushing rose-purple after fertilisation. Stamen filaments white of two types, long 1.5–2.4 mm long and short 0.8–1.4 mm. Anthers cream, 0.5–1.0 × 0.3–0.65 mm. Style 1.1–2.0 mm long, white. Stigma 1.5–4.0 × 0.9–1.5 mm, white, clavate, surrounded by anthers at anthesis. Capsule 30–75 mm long, densely strigulose; pedicel 6–12 mm long. Seeds 0.9–1.1 × 0.3–0.4 mm, brown, reticulate-mammilate to reticulate-papillose, obovoid, without a chalazal callus, apex shortly beaked; coma 7.0–10.5 mm long, white, breaking off readily.
Similar taxa
Easily distinguished from other New Zealand epilobia by its ecological preference for damp sandy ground in coastal habitats, large size, stoloniferous, decumbent growth habit with only weakly ascendent, branch tips, erect inflorescences, glabrescent stems, yellow-green, green to red-tinged, glabrous, narrowly ovate to ovate leaves with rounded to truncate bases and obtuse apcies and whose leaf margins are densely and evenly serrulate, bearing 16–40 teeth either side, and by the densely grey-strigulose (glandular and glandular hairs absent) inflorescences and capsules, and white flowers (which are only faintly rose-tinged after fertilisation). The species is superficially similar to E. rotundifolium as both have similar leaf shape and growth habit, but the teeth on the leaves of E. billardierianum ar much finer than those of E. rotundifolium, the flowers on E. billardierianum are significantly larger, and the dense covering of hair on E. billardierianum is more obviously white gray in colour. In New Zealand at least Epilobium billardierianum has no similarity whatsoever to the strictly erect, much-branched, grey-coloured, E. cinereum (see Taxonomic Notes under E. cinereum) with which it sometimes grows. Both species are amply distinct from each other, and as far as is known do not hybridise with each other in the wild.
Distribution
Indigenous. New Zealand: North Island, South Island, Stewart Island/Rakiura, Chatham Islands. Also Australia (New South Wales, Victoria, South Australia and Tasmania).
Habitat
Coastal. Usually on sparsely vegetated damp sand flats, or sandy ground bordering slow flowing streams, lagoons, ponds and lake margins. Often found in association with oioi (Apodasmia similis), wiwi (Ficinia nodosa) and Juncus spp. On the Chatham Islands, E. billardierianum is occasionally found inland growing on sandy ground in seasonally damp ground or around permnanent water bodies.
Substrate details
Sand
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 | At Risk – Declining | Qualifiers: DPR, DPS, DPT, SO
Detailed taxonomy
Family
Synonyms
Epilobium billardiereanum (Ser.) DC. subsp. billardiereanum
Taxonomic notes
Raven & Raven (1976) prefer to treat Epilobium billardierianum as E. billardierianum subsp. billiardierianum, and E. cinerium as E. billardierianum subsp. cinerium. 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. Furthermore, hybrids between both subspecies 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
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–March
Fruiting
December–July
Propagation technique
Easily grown from rooted pieces and fresh seed. Does best planted in full sun in a damp sandy soil. Inclined to be weedy and probably best left for restoration plantings into dune field rather than general cultivation.
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]
FACW: Facultative Wetland
Usually is a hydrophyte but occasionally found 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.
billardiereanum: Named after Jacques Houttou de Labillardiere (1755-1834), 19th century French botanist who described several New Zealand plants
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.
EPIBIL
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 | Threatened – Regionally Endangered | Qualifiers: DPR, DPS, DPT, EF, SO, Sp
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 PH, Raven TE. 1976. The genus Epilobium in Australasia. New Zealand DSIR Bulletin 216. Government Printer, Wellington, NZ. 321 p.
Webb CJ, Simpson MJA. 2001. Seeds of New Zealand Gymnosperms and Dicotyledons. Manuka Press, Christchurch. 428 p.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 28 August 2011. Description prepared by P.J. de Lange (28 August 2011) adapted from Raven & Raven (1976) and Webb & Simpson (2001).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Epilobium billardiereanum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/epilobium-billardiereanum/ (Date website was queried)