Epilobium petraeum
Common names
rock willow herb
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 | At Risk – Naturally Uncommon | Qualifiers: RR, Sp
Category
Vascular
Structural class
Herbs - Dicotyledons other than Composites
Flower colours
White
Detailed description
Compact, densely spreading, glabrous herb producing shrublets up to 400 x 100 mm. Old stems prostrate to spreading; new stems erect, red; not rooting at nodes. Petiole 5-7 mm, slender, channelled, appressed to the stem or slightly spreading. Leaves 15-24 x 4-7 mm, opposite, ovate, elliptic, or broad-elliptic, glossy, erect or spreading, longer than internodes, 3-5 teeth on each margin, upper surfaces dark-green and sometimes flushed red, uppersides red, margin and midrib usually red, base cuneate, apex obtuse to retuse. Inflorescence terminal, conspicuous; flowers perfect, erect; pedicel 2-4 mm long, green; bud pink. Sepals 4, 4-4.5 x 1.2-1.4 mm, oblong, not keeled, red, apex acute. Petals 4, 5-6 x 1.9-2.1 mm, obovate, white, apex notch 0.5-0.8 mm deep. Floral tube 1-1.2 mm deep, c. 2 mm wide. Ovary 12-14 mm, green; style 2.3 mm, white; stigma 1 x 0.4 mm, yellow; filaments white, unequal, longer 2-2.5 mm, shorter 1-1.2 mm. Capsule 35-55 x 1.4-1.8 mm, scarlet-red; pedicel 10-24 mm, scarlet-red. Seeds 1-1.1 x 0.4-0.45 mm, pale brown, papillose but usually flat on one surfave; proximal end constricted with acute apex; chalazal end with a very short, inconspicuous neck; coma 4-5 mm long, white, caducous.
Similar taxa
Distinguished by the low, spreading, compact habit, all parts glabrous, red stems, opposite, dark-green and glossy leaves with the upper midrib usually red, the leaves not obscuring the internodes, a floral tube 1-1.2. mm deep, and papillose 1-1.1. x 0.4-0.45 mm seeds with a non-persistent coma. It is most similar to E. brevipes Hook.f. which is a glabrescent shrub of similar habitats, with leaves that are initially opposite becoming alternate toward the stem apices. The leaves are narrowly elliptic to elliptic with acute rather than obtuse to retuse apices. A key difference is that the leaf apex in E. breivpes has a distinct apiculus (like a lump of gum) which is absent in E. petraeum. Furthermore the stem leaf junction of E. brevipes has a miniscule tuft of strigulose hairs.
Distribution
Endemic. South Island from the Kaikoura Ranges (Mt Fyffe) south to the Mt Cook Region of Canterbury.
Habitat
A species of exposed, steep, partially stable, sparsely vegetated greywacke rock outcrops, stable to partially stable scree in and near margins of rock outcrops, and occasionally found on partially stable and exposed stream margins.
Threats
A widespread, naturally uncommon, biological sparse species of high alpine rock habitats. There is no evidence of decline.
Detailed taxonomy
Genus
Family
Synonyms
None
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Ecology
Flowering
December - January
Fruiting
January - March
Life cycle and dispersal
Minute pappate seeds are wind dispersed (Thorsen et al., 2009).
Propagation technique
Easily grown in a pot kept in an alpine house or in a rock garden. Prefers a fertile, free draining soil and full sun. Intolerant of warm, humid climates.
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.
petraeum: Loves rocks
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.
EPIPET
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 | At Risk – Naturally Uncommon | Qualifiers: RR, Sp
2012 | At Risk – Naturally Uncommon | Qualifiers: RR, Sp
2009 | At Risk – Naturally Uncommon
2004 | Sparse
Referencing and citations
References and further reading
Heenan, P. B. 1996: Epilobium petraeum (Onagraceae), a new species of alpine willow-herb from New Zealand. New Zealand Journal of Botany 34(1): 41-45.
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
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 6 June 2004. Description adapted from Heenan (1996).