Juncus ensifolius
Common name
iris-leaved rush
Synonyms
Verojuncus ensifolius (Wikstr.) Záveská Drábková & Proćków
Family
Juncaceae
Flora category
Vascular – Exotic
Structural class
Rushes & Allied Plants
Conservation status
Not applicable
Brief description
Leafy rush to 70 cm tall, leaves flattened an iris-like (sword-shaped), plant blue-green with 1–3 spherical flowerheads made up of many dark-brown to black flowers/capsules (fruit).
Distribution
Scattered and local from Bay of Plenty, Westland and Canterbury.
Habitat
Swampy roadsides and riverine wetlands.
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]
FACW: Facultative Wetland
Usually is a hydrophyte but occasionally found in uplands (non-wetlands).
Detailed description
Loosely tufted or forming open colonies, less frequently densely tufted; rhizome slender, ± far-extending. Stems 15–70 cm high, laterally compressed, almost winged at lower nodes, cauline leaves 2–3. Leaves ensiform, ± curved, ± flat, blue-green, longitudinal and transverse septa visible externally, often incomplete. Inflorescence of 1–3 large, many-flowered, usually blackish, globose clusters, causing taller stems to incline. Tepals 2.5–3 mm long, all ± equal, acute to acuminate. Stamens 3–6. Capsule c. 3 mm long, > tepals, oblong, shortly mucronate, dark brown to black.
Similar taxa
Only J. ensifolius and the native J. prismatocarpus have flattened multitubular septate leaves. J. ensifolius itends to be sward-forming and has 2–3 black globose flower clusters rather than the clumped plants with many-branched inflorescences green or pink flower clusters of J. prismatocarpus.
Flowering
Summer
Flower colours
Black, Brown
Fruiting
Autumn
Life cycle
Seed dispersed by animals, water or contaminated machinery.
Year naturalised
1940
Origin
Western North America
Reason for introduction
Unknown, seed or soil contaminant.
Control techniques
Not controlled in New Zealand.
Etymology
juncus: From the Latin jungere ‘to tie or bind’, the stems of some species being used to make cord (Johnson and Smith)
Taxonomic notes
Subgenus Juncus, Section Iridifolii (Septati) Kirschner (2002: Juncaceae 2)
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.
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA). Features description from Healy and Edgar (1980).
References and further reading
Champion, P. et al. 2020. Freshwater Invasive Species of New Zealand 2020. NIWA publication. https://docs.niwa.co.nz/library/public/FreInSpec.pdf
Healy, A. J. 1982. Identification of weeds and clovers. New Zealand Weed and Pest Control Society Publication. Editorial Services Limited, Featherston. 299 p.
Healy, A. J.; Edgar, E. 1980. Flora of New Zealand, Volume III. Adventive Cyperaceous, Petalous and Spathaceous Monocotyledons. Government Printer, Wellington. 220 p.
Johnson, P. N.; Brooke, P. A. 1989. Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319 p.
Johnson, A. T.; Smith, H. A. 1986. Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd, Buckenhill, UK.
Kirschner, J. (compiler) (2002). Juncaceae 2: Juncus subg. Juncus, Species Plantarum: Flora of the World Part 7: 1–336.
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.