Epilobium atriplicifolium
Common name
willowherb
Synonyms
Epilobium alsinoides subsp. atriplicifolium (A.Cunn.) P.H.Raven et Engelhorn
Family
Onagraceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Herbs - Dicotyledons other than Composites
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.
EPIATR
Chromosome number
2n = 36
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Not Threatened
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Distribution
Endemic. New Zealand: North, South, Stewart, Chatham Antipodes, Campbell and Auckland Islands.
Features
Variable, suberect to erect, much-branched, matted, perennial herb 20-360 mm tall, bearingnumerous leafy stolons arising from the base; plants with retrorsely (rarely antrorsely) appressed or erect hairs decurrent from the petiole margins, the hairs running out on the margins of leaves, or strigulose all around. Leaves opposite, alternate in the inflorescence, lamina usually much shorter than subtending internodes, sessile or on short petioles up to 2 mm long, dull bluish-green, glabrous except for a few hairs near the base on the margins, the lateral veins not prominent, 2-3 on each side of the midrib; lamina 8-18 x 4-5 mm, narrowly elliptic to ovate, apex acute, base rounded, margins serrulate, with 1-6 teeth on each side. Inflorescence erect, the flowers scattered down the stem. Flowers erect, Ovaries 6-15 mm long, glabrous (rarely weakly to densely strigulose), on pedicels 1-17 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 1.0-2.7 mm long, those of shorter stamens 0.6-1.6 mm long, the anthers of the longer stamens dehiscing first and shedding pollen directly on to the stigma after the flower opens. Styles 1.2-3.2 mm high, white; stigma 0.8-2.6 x 0.3-1.2 mm, white, clavate, surrounded by anthers of at least the longer and usually both sets of stamens at anthesis. Capsule 17-36 mm long, on pedicels 10-90 mm long; blue-green, glabrous (rarely densely strigulose). Seeds 0.7-1.2 x 0.3-0.6 mm, pale orange-brown to orange, obovoid or narrowly obovoid, testa finely reticulate-papillate, apex rounded; coma 5-7 mm long, white, caducous.
Similar taxa
Epilobium atriplicifolium differs from the allied E. alsinoides and E. tenuipes by having finely reticulate-papillate rather than finely reticulate seeds, and pedicels which elongate to 10-90 mm (usually 10-40 mm long) long in fruiting specimens (10-80 mm but usually 20-80 mm in E. alsinoides). From E. elegans, with which it grows it differs from E. elegans by its narrower leaves, smaller flowers, and longer-pedicellate condition. From Epilobium cockayneanum with which it also grows in the Central North Island and South Island it differs by its taller, less matted growth habit, narrower, less deeply toothed leaves (leaves of E. cockayneanum are broadly ovate, ovate-elliptic to ovate-oblong, 5-14 x 6-8 mm, and more deeply toothed).
Flowering
November - March
Fruiting
January - May
Life cycle
Minute pappate seeds are wind dispersed (Thorsen et al., 2009).
Propagation technique
Easily grown from fresh seed and rooted pieces. Dislikes humidity and prone to powdery mildew in humid climates. Inclined to be weedy.
Threats
Not Threatened. However, E. atriplicifolium is seemingly scarce (apparently naturally so) north of the Waikato.
Etymology
epilobium: From the Greek epi- ‘upon’ and lobos ‘a pod’, the flowers appearing to be growing on the seed pod.
atriplicifolium: Leaves resembling Atriplex, unrelated plant
Where To Buy
Not commercially available
Notes on taxonomy
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 ( see also comments under E. cockayenanum).
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (22 October 2012).Description adapted from Raven & Raven (1976).
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.
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.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Epilobium atriplicifolium Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/epilobium-atriplicifolium/ (Date website was queried)