Juncus holoschoenus var. holoschoenus
Biostatus
Native
Category
Vascular
Structural class
Rushes & Allied Plants
Flower colours
Green, Red/Pink
Detailed description
Tufted, shortly rhizomatous perennial, bright-green rush up to 750mm tall. Stems stout, erect, circular in cross-section, internal transverse septa absent or just evident. Leaf-sheath pale green to almost white, 30–50mm long, incompletely septate, auricles 2, obtuse. Leaves 5–10, 150–300mm long, linear, erect to curving, circular to semi-compressed, hollow, unitubular, transversely septate across whole width; leaf tip acuminate. Inflorescence rather stout, terminal, cymose; 2–5 branched, bearing 2–8, globular, 20–30mm diameter, 10–30-flowered fascicles at branch apices; subtending bract leafy, < inflorescence, septate across whole width. Flowers 3.5–5.0mm diameter; tepals equal, acuminate, green to red-green. Stamens 6. Capsules 4.5 × 1.5mm, more or less equal in length to tepals, ovate-lanceolate, triquetrous, tapered to a distinct, mucronate apex.
Similar taxa
Juncus holoschoenus var. multiflorus is similar but this is a species of very open, disturbed habitats dominated by naturalised species. From J. holoschoenus var. holoschoenus it differs by its more slender, weakly tufted almost trailing stems, rather than the stout, erect, much taller, few-stemmed growth form typical of var. holoschoenus, and by the more numerous (up to 40, up to 8 in var. holoschoenus), smaller flower clusters.
J. holoschoenus var. holoschoenus is similar to the indigenous J. prismatocarpus and the introduced J. fockei. From J. prismatocarpus it can be distinguished by its rolled, rather than flat leaves with transverse septa only, and flowers with 6 rather than three stamens. From J. fockei it can be distinguished by the shorter, slightly tapered capsule which is more or less equal in length to the tepals, and much denser, more robust and fewer-flowered inflorescences.
Distribution
Indigenous. Common in Australia—although J. holoschoenus is a species complex and, when the segregate entities are fully resolved, it may turn out to be much less common there than currently believed. In New Zealand, though reported widely from North, South and Chatham Islands, critical comparison of herbarium specimens shows that most recent (and historic) records are based on J. holoschoenus var. multiflorus Carse whose taxonomic status, whilst unclear (see comments made of it in Flora of New Zealand, Vol. 2), is clearly not the same as the older New Zealand collections of J. holoschoenus and is probably the result of an Australian introduction of one of their J. holoschoenus complex.
Habitat
Coastal and lowland to subalpine eutrophic to oligotrophic wetlands. Always found growing in shallow water.
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 | Threatened – Nationally Critical | Qualifiers: CD, EF, OL, SO?
Threats
Not clear. This rush has declined rapidly over the last 120 years and is now only known with certainty from relatively weed-free sub-alpine mires and frost flats. It seems plausible that it declined through competition from other similar introduced rushes or a host of other exotic wetland weeds that now dominate many wetland systems that this species once occupied. Examination of herbarium specimens suggests this rush might never have been common in New Zealand. Perhaps it was a recent trans-Tasman arrival, which was in the process of establishing itself, when other exotic weeds were introduced into the wetland systems it evidently favours. One thing is clear, J. holoschoenus var. holoschoenus is now seriously at risk of extinction in this country.
Detailed taxonomy
Genus
Family
Synonyms
Verojuncus holoschoenus (R.Br.) Záveská Drábková & Proćków
Taxonomic notes
Proćków et al. (2023) proposed a taxonomic segregation of Juncus into six genera based on molecular and morphological evidence. Whilst it has long been recognised that the current circumscription of Juncus includes morphologically divergent taxa—reflected in the recognition of numerous subgenera and sections—the consensus view of the NZPCN website taxonomy subcommittee, taking into consideration advice from Australian Juncus expert Dr Karen Wilson (NSW Herbarium) and others in Europe is that the generic segregations proposed need further consideration and testing. Accordingly, it has been decided to maintain the current broad circumscription of Juncus, but to include all new names as synonyms in factsheets. We thank, in particular, Dr Wilson for her helpful comments.
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
October–December
Fruiting
December–May
Life cycle and dispersal
Mucilaginous seeds are dispersed by attachment, wind and water (Thorsen et al., 2009).
Propagation technique
Easily grown from division of whole plants and from fresh seed.
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
Cultivation
Not commericially available. Some plants are held by specialist growers.
Etymology
juncus: From the Latin jungere ‘to tie or bind’, the stems of some species being used to make cord (Johnson and Smith)
Chromosome number
2n = 106
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 | Threatened – Nationally Critical | Qualifiers: DP, EF, OL, SO?
2012 | Threatened – Nationally Critical | Qualifiers: EF, OL, SO
2009 | Threatened – Nationally Critical | Qualifiers: CD, DP, EF, SO
2004 | Threatened – Nationally Endangered
Referencing and citations
References and further reading
de Lange, P.J.; Heenan, P.B.; Norton, D.A.; Rolfe, J.R.; Sawyer, J.W.D. 2010: Threatened Plants of New Zealand. Canterbury University Press, Christchurch.
Johnson, A. T. and Smith, H. A. 1986. Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd, Buckenhill, UK.
Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.
Proćków, J., Záveská Drábková, L. 2023. A revision of the Juncaceae with delimitation of six new genera: nomenclatural changes in Juncus. Phytotaxa 622(1): 17–41.
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 the NZPCN by P.J. de Lange 1 September 2006. Description by P.J. de Lange and subsequently published in de Lange et al. (2010) - see also Moore & Edgar (1970) - a description which also includes var. multiflorus.
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Juncus holoschoenus var. holoschoenus Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/juncus-holoschoenus-var-holoschoenus/ (Date website was queried)