Epilobium macropus
Common names
willowherb
Biostatus
Native – Endemic taxon
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
White
Detailed description
Dense, creeping, mat-forming perennial herb of sodden ground, the stems 20-200 mm long, creeping and rooting below; stems pubescent all round with short bristly hairs. Leaves usually crowded and overlapping or shorter than the internodes they subtend, opposite, with the uppermost occasionally alternate, bright yellowish-green, not shining, paler and occasionally slightly glaucous beneath, the lateral veins not obvious, 2-3 on each side of the midrib, elliptic to narrowly ovate, acuminate at the apex, obtuse to acute at the base, 6-15 × 3-8 mm, entire or very obscurely denticulate with c.2-4 minute teeth along each margin; petioles 2-3 mm long, distinct. Flowers arising individually from the axils of the leaves. Ovaries 15-20 mm long, glabrous or sparsely clothed with short erect hairs, often purplish, on a pedicel 5-25 mm long. Floral tube 1.3-2.0 × 1.5-2.2 mm. Sepals 3.0-6.0 × 1.3-1.8 mm, often tinged purple, not keeled, chartaceous, membranous, glabrous or sparsely invested with short erect hairs. Petals 6.5-12.0 × 4.0-8.0 mm, notch 1.5-3.0 mm deep, white, very rarely flushed pink initially but flushing pink after pollination. Stamens filaments white, of two types: long (2.5-5.0 mm long) and short (1-3 mm long), Anthers 0.9-1.0 × 0.4-0.5 mm,bright yellow. Style 4.5-9.0 mm long, white but purplish near the base, stigma 1.2-2.7 x 0.7-1.6 mm, broadly clavate, held above anthers in early anthesis. Capsule 30-65 mm long, stout, glabrous, on a pedicel 10-120 mm long. Seeds 0.5-1.0 mm long, orange to orange-brown, oblong-obovate, elliptic-obovate or obovate, finely reticulate; coma 7.5-11.0 mm long, orange to orange-brown; coma 2.5-7.0 mm long, white, usually persistent.
Similar taxa
A very distinctive species easily recognised by its mat-forming growth habit and ecological preference for growing in running water. Raven & Raven (1976) suggest (on morphological grounds) a close relationship with E. chionanthum with which it has a superficial resemblance and both species are distinguished from all other New Zealand epilobia by sharing a orange to orange-brown, long persistent coma. From E. chionanthum, E. macropus differs by the stems which are evenly pubescent throughout with short, erect, bristly hairs (rather than mostly glabrous but strigulose along lines decurrent from the margins of the petioles below), with only the very uppermost leaves alternate (mostly opposite rarely with a few alternate in the inflorescence), and by the fruiting pedicels 10-120 mm long (12-28 mm long in E. chionanthum).
Distribution
Endemic. New Zealand: North Island (Central Volcanic Plateau and main axial ranges south), South Island (mostly easterly).
Habitat
Montane to alpine on the margins of (and sometimes partially immersed in) mountain streams, seepages and soaks.
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
Detailed taxonomy
Family
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
November- March
Fruiting
FR:
Life cycle and dispersal
Minute pappate seeds are wind dispersed (Thorsen et al., 2009).
Propagation technique
Easily grown from fresh seed and rooted pieces. However to flourish it needs to be planted on the margins of streams or kept in partially immersed pots with the water changed frequently. Does not tolerate high humidity and drought. Epilobium macropus is a very attractive species that despite being tricky to cultivate deserves to be more widely grown.
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]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Other information
Where To Buy
Not commercially available
Etymology
epilobium: From the Greek epi- ‘upon’ and lobos ‘a pod’, the flowers appearing to be growing on the seed pod.
macropus: Big foot
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.
EPIMAC
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
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.
Otago: 2024 | Regionally Not Threatened
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.
Thorsen, M.J.; Dickinson, K.J.M.; Seddon, P.J. 2009: Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285-309.
Webb, C.J.; Simpson, M.J.A. 2011: Seeds of New Zealand Gymnosperms and Dicotyledons. Christchurch, Manuka Press.
Attribution
Fact sheet prepared for NZPCN b: P.J. de Lange (28 August 2011). Description 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 macropus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/epilobium-macropus/ (Date website was queried)