Juncus holoschoenus var. holoschoenus
Synonyms
None
Family
Juncaceae
Flora category
Vascular – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Rushes & Allied Plants
Chromosome number
2n = 106
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 | Threatened – Nationally Critical | Qualifiers: EF, OL, SO
Previous conservation statuses
2009 | Threatened – Nationally Critical | Qualifiers: CD, DP, EF, SO
2004 | Threatened – Nationally Endangered
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.
Features
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
J. holoschoenus is most similar to the indigenous J. prismatocarpus and 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.
Flowering
October to December
Flower colours
Green, Red/Pink
Fruiting
December to May
Life cycle
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.
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.
Etymology
juncus: From the Latin jungere ‘to tie or bind’, the stems of some species being used to make cord (Johnson and Smith)
Where To Buy
Not commericially available. Some plants are held by specialist growers.
Cultural Use/Importance
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.
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.
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.
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
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)