Epilobium alsinoides
Common names
willowherb
Biostatus
Native – Endemic taxon
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
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Simplified description
A perennial herb. Low, delicate and matted in form. Covered everywhere with strigulose pubescence. Found in grassland from sea level to low alpine. Fairly inconspicuous, due to its low stature and often sparse foliage.
Flower colours
White
Detailed description
Delicate, decumbent, matted, much-branched perennial herb up to 200 mm tall, bearing numerous leafy stolons arising from the base; plants densely strigulose-pubescent, hairs usually antrorsely appressed. Leaves on distinct petioles 1-2 mm long, opposite, alternate in the inflorescence, dull bluish-green, occasionally with a few hairs near the base on the margins, the lateral veins not prominent, 2-3 on each side of the midrib; lamina shorter than subtending internodes, 3.0-8.0 x 2.0-5.5 mm, ovate, with 2-4 indistinct teeth on each side (rarely entire), apex acute to obtuse, base rounded. Inflorescence erect, the flowers scattered down the stem. Flowers erect, Ovaries 6-15 mm long, densely strigulose, on pedicels 25-50 mm long. Floral tube 0.5-1.5 mm deep, 0.7-2.2 mm diameter, glabrous or strigulose externally. Sepals 2.0-4.5 x 0.8-1.5 mm, not keeled, glabrous or strigulose. Petals 2.8-6.0 x 1.8-4.5 mm, notch 0.7-2.0 mm deep; white, sometimes flushing pink after pollination. Anthers 0.4-0.9 x 0.25-0.5 mm, cream or yellow; filaments white, those of longer stamens 0.6-1.5 mm long, those of shorter stamens 0.3-0.8 mm long, the anthers of the longer stamens dehiscing first and shedding pollen directly on to the stigma after the flower opens. Style 1.0-1.7 mm high, white; stigma 1.0-1.5 x 0.4-0.65 mm, white, clavate, surrounded by anthers of at least the longer and usually both sets of stamens at anthesis. Capsule 25-30 mm long, on pedicels 10-60 mm long; blue-green, densely strigulose. Seeds 0.6-1.0 x 0.2-0.3 mm, pale orange-brown or orange, oblong-obovate, obovate, testa finely reticulate, apices rounded; coma 4.5-7.0 mm long, white, caducous.
Similar taxa
Epilobium alsinoides is most often mistaken for the allied E. tenuipes, and occasionally E. atriplicifolium, both of with co-exist with the species across much of its range. Epilobium alsinoides differs from the allied E. atriplicifolium by having finely reticulate rather than papillose seeds, and pedicels which elongate to 10-80 mm (usually 20-80 mm long) long in fruiting specimens (10-90 mm but usually 10-40 mm in E. atriplicifolium). The leaves of E. atripilcifolium can some sometimes have hairs running up their margins, but E. alsinoides is not known to share this feature. From E. tenuipes, E. alsinoides is separated by the ovate rather than narrowly elliptic or linear leaves, which are typically shorter than the internodes they subtend. In Epilobium tenuipes the mature capsules are usually conspicuously elevated above the leafy stems while they are much less so in E. alsinoides. Unlike E. tenuipes, E. alsinoides has white looking strigulose hairs covering the capsule and sepals.
Distribution
Endemic. New Zealand: North and South Islands (scarce in East Coast of the North Island, and apparently absent in the South Island, south of Nelson and northern Marlborough).
Habitat
Sea level to low alpine. Usually in open grassland or on partially shaded, seasonally damp eroding banks
Threats
Not Threatened. However, E. alsinoides is seemingly scarce (apparently naturally so) north of the Waikato.
Detailed taxonomy
Genus
Family
Synonyms
Epilobium alsinoides A.Cunn. subsp. alsinoides
Taxonomic notes
Raven & Raven (1976) adopted a very conservative treatment for New Zealand Epilobium. In that treatment they recognised Epilobium atriplicifolium and E. tenuipes as subspecies of E. alsinoides. They also included with E. alsinoides subsp. atriplicifolium, E. cockayneanum (treated as a species here) and within subsp. tenuipes they merged E. elegans (also accepted at species rank here). Raven & Raven (1976) argued for subspecies rank and species merger on the basis of what they saw as intergrading forms between E. atriplicifolium, E. cockayneanum, E. elegans and E. tenuipes in the South Island. They did note that intergrading was not evident in the North Island, where the “major entites…are sharply distinct” but they suggested that this had to do with the effectively autogamous breeding system of these taxa, and while they accepted that intergrading forms occurred within the most “highly disturbed vegetational formation in New Zealand” (i.e. tussock grasslands) suggesting that such intergrades were not natural, they nevertheless felt justified in their highly conservative treatment. Subsequently field botanists have largely followed the unpublished views of the late Tony Druce who continued to recognise as species E. atriplicifolium, E. cockayneanum, E. elegans and E. tenuipes. For want of a thorough, multi-marker DNA-based revision of New Zealand Epilobium, for now at least it seems preferrable to follow Druce (1993) rather than Raven & Raven (1976) whose treatment of Epilobium, whilst understandable for its time, seems inconsistent.
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
November - January
Fruiting
January - May
Propagation technique
Easily grown from fresh seed and rooted pieces. Dislikes humidity and prone to powdery mildew in humid climates. Inclined to be weedy.
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]
FACU: Facultative Upland
Occasionally is a hydrophyte but usually occurs 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.
alsinoides: From the Greek alsos ‘grove’ often the habitat of chickweeds, meaning like chickweed
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.
EPIALS
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
2012 | Not Threatened
2009 | Not Threatened
2004 | Not Threatened
Regional conservation statuses
Auckland: 2025 | Regionally Extirpated | Qualifiers: EW
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.
Otago: 2025 | 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 “Conservation Status of Indigenous Vascular Plants in Otago, 2025” Jarvie S et al. (2025) report.
Referencing and citations
References and further reading
Druce, A.P. 1993: Indigenous vascular plants of New Zealand. Ninth Revision. Unpublished Checklist held at Landcare Research, Lincoln, New Zealand.
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. 2011: Seeds of New Zealand Gymnosperms and Dicotyledons. Christchurch, Manuka Press.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (22 October 2012).Description adapted from Raven & Raven (1976) and Webb & Simpson (2001).