Empodisma robustum
Common names
wire rush
Biostatus
Native
Category
Vascular
Structural class
Rushes & Allied Plants
Flower colours
Yellow
Detailed description
Dioecious, perennial herb producing numerous, branched, flexuose culms collectively forming densely interwoven tangles. Rhizome rather robust for plant, erect, up to 12 mm diameter, covering with light brown, imbricating scale-like sheaths and very thick tufts of brown hairs; roots numerous, mostly horizontal-ascending rather than descending, 1.2–1.8 mm diameter, densely covered in pinkish-white root hairs. Culms 0.38–2.2 m, 0.9–2.2 mm diameter, much-branched, flexuous, terete or slightly flattened and grooved on one side, glabrous, dark green to dark brown, erect when short, otherwise more or less prostrate to ascending, widely spreading and lianoid. Leaves reduced to mucronate sheaths, 5.2–21.0 mm long, closely appressed to culm, spaced 20–70 mm apart, initially light green to light brown maturing dark brown, margin entire; cilia protruding through the mouth of the sheath as white tufts of woolly white hairs; hairs arising from the outer scale of the axillary bud enclosed within sheath; mucro persistent, 2.2–7.5 mm long, initially light green maturing dark brown, fine, sharp-pointed (accicular), strongly reflexed from leaf sheath. Spikelets brown, distant within uppermost sheaths. Male spikelets 1–2, 6.8–9.0 mm long, 1–6-flowered, 1 sessile and 1 stalked, each borne within a hard, mucronate sheath; tepals 6, narrow-linear, acute; stamens 3, filaments slender, > tepals, anthers 1.9–2.5 m, exserted beyond the floral bract. Female spikelets 5.8–8.9 mm, solitary within 1–3 uppermost, bearded, obtuse sheaths, 1-flowered, subtended by 2 imbricate, empty floral bracts; tepals 4–6, very small, hyaline; styles 3, free. Fruit a hard nut, 2.7 mm long, dark brown, ovoid, protruding over persistent tepals, sessile on a thick receptacle.
Similar taxa
Empodisma minus differs from E. robustum by its diminutive stature and slender growth habit; culms mostly < 1 mm in diameter, sheaths mostly < 7.5 mm long and spikelets generally < 6.0 mm long. Readily distinguished from the two other New Zealand tall restiad genera Sporadanthus and Apodasmia by the mostly widely spreading, decumbent, trailing to lianoid growth habit, and 1–6-flowered male and 1-flowered female spikelets.
Distribution
Endemic. New Zealand: North Island (Te Aupouri Peninsula south to the lower Waikato).
Habitat
Empodisma robustum is restricted to ombrotrophic raised peat bogs where it often coexists with Sporadanthus ferrugineus, fens and gumland heathland peats. It is often locally abundant.
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.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – these interim threat classification statuses has not been assessed by the NZTCS panel.
- 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 – Declining
Detailed taxonomy
Family
Restionaceae
Synonyms
None first described in 2012.
Taxonomic notes
The description (as Calorophus minor) in Flora II (Moore & Edgar 1970) includes two elements which are now treated as two species Empodisma minus and E. robustum.
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
August–October
Fruiting
November–March
Propagation technique
Easily grown from fresh seed and by the division of established plants. Despite its natural restriction to acidic wetlands. Empodisma robustum can be easily grown in a range of media though it does best in full sun in a permanently damp soil.
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
Etymology
empodisma: Tangle-foot
robustum: Sturdy
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.
EMPROB
Chromosome number
2n = 24
Previous conservation statuses
2017 | At Risk – Declining
2012 | Not Threatened
2009 | Not Threatened
Referencing and citations
References and further reading
Moore LB, Edgar E. 1970. Flora of New Zealand, Volume II. Indigenous Tracheophyta: Monocotyledones except Gramineae. Government Printer, Wellington, NZ. 354 p.
Wagstaff SJ, Clarkson BR. 2012. Systematics and ecology of the Australasian genus Empodisma (Restionaceae) and description of a new species from peatlands in northern New Zealand. Phytokeys 13: 39-79. https://doi.org/10.3897/phytokeys.13.3259.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange 26 June 2012. Description from Wagstaff & Clarkson (2012).
NZPCN Fact Sheet citation
Please cite as: de Lange, P.J. (Year at time of access): Empodisma robustum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/empodisma-robustum/ (Date website was queried)