Schoenus fluitans
Common names
floating schoenus
Biostatus
Native
Category
Vascular
Structural class
Sedges
Detailed description
Densely tufted or floating, usually dark red sedge of shallow pools, slowly flowing streams or muddy ground left by receding waters. Culms up to 600 × 0.5 mm, rooted at base, in terrestrial forms rooting freely at leaf nodes, otherwise rest of culm floating. Leaves 20–100 mm long, dark red or green, in floating forms distant, otherwise rather tufted, filiform, flaccid in aquatic plants, more rigid in terrestrial plants; margins slightly scabrid toward leaf apices; sheath very long, green or red-brown, margins membranous to chartaceous, prolonged toward apex as a ligule. Spikelets 2–4-flowered, in terrestrial forms often buried within leaves and scarcely distinguished, in floating forms more obvious; 7–12 mm long, narrow-linear, solitary, terminal, subtended by a glume-like bract, or rarely 2–3 spikelets distant at the end of the culm, the lower ones subtended by more leaf like bracts. Glumes 3–4, lanceolate, obtuse, membranous, light red or pale cream; all fertile or the lowermost empty. Hypogynous bristles 0. Stamens 3. Style-branches 3. Nut 2 × 1 mm, obovoid, brown with black patches or entirely black.
Similar taxa
A very distinctive sedge which is unlikely to be confused with any other species. Plants may be confused with sterile plants of Juncus bulbosus, which now grows in similar habitats and can be coloured dark red. However that species has much finer, septate leaves. Within the New Zealand species Schoenus fluitans appears to be closely allied to S. maschalinus, and terrestrial plants of S. fluitans or those left stranded by receding waters in particular have some resemblance to it. However, S. maschalinus is a much smaller, more widely creeping plant (up to 1 m diameter) of lowland to montane wetlands and damp ground in forest. It is always coloured bright green (never red), is much more gracile, and has 6 hypogynous bristles (0 in S. fluitans), and a white rather than black or brown mottled black nut. Both species share the same chromosome number (2n = 10), and nrDNA ITS sequences place them as sister species.
Distribution
Indigenous. In New Zealand known from the North Island where it is only found in the Central Volcanic Plateau (from the southern Kaingaroa Plain south) and the Ruahine Ranges. In January 2006 it was discovered on Chatham (Rekohu) Island. Common in Australia.
Habitat
Mainly upper montane to subalpine (800–1500 m a.s.l.) bogs, tarns, slow flowing streams, muddy ground in and around seasonal pools, and on shallow lake margins. On the Chatham Islands S. fluitans has been gathered from restaid peat bogs in shallow pools amongst Sporadanthus traversii (F.Muell.) F.Muell.
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: Sp, DPS, DPT, RR, SO
Threats
A usually upland species which appears to be locally common over parts of the Central Volcanic Plateau. In some parts of this range it faces competition from Juncus bulbosus, and there is some evidence that it has become extinct in the northern part of its range due to that aggressive weed. The 2006 discovery on the Chatham Islands was accidental and its exact status there has yet to be determined.
Detailed taxonomy
Genus
Family
Synonyms
None
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
December
Fruiting
January - April
Propagation technique
Easily grown in a peaty soil within a partially submerged pot. Does best in semi-shade. However, it can be rather fickle and difficult to maintain for any length of time. In cultivation plants usually change colour for dark red to lime green.
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
schoenus: Rush
fluitans: From the Greek fluito (floating)
Chromosome number
2n = 10
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: DP, RR, SO, Sp
2012 | At Risk – Naturally Uncommon | Qualifiers: RR, SO, Sp
2009 | At Risk – Declining | Qualifiers: PD, RR, SO, Sp
2004 | Range Restricted
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.
Attribution
Fact sheet prepared for NZPCN by P.J. de Lange (August 2006). Description adapted from Moore & Edgar (1970).
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): Schoenus fluitans Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/schoenus-fluitans/ (Date website was queried)