Isolepis lenticularis
Biostatus
Native
Category
Vascular
Structural class
Sedges
Detailed description
Annual or short-lived perennial, forming diffuse to dense floating or terrestrial mats. Roots minute, rhizomes thread-like, green above ground. Culms 10–47(or more) mm , 0.2–1.1 mm diam., with one or more internodes, peduncle 10–190 mm, 0.2–0.9 mm diam. Leaf-sheath 3–25 × 0.3–1.7 mm, green or brown, lamina 2–80 × 0.2–1.1 mm. Inflorescence terminal, not proliferating; bract 2–12 × 0.3–1.3 mm. Spikelet 1, 2.4–9.4 × 0.7–2.7 mm, with 4–28 glumes. Glumes 1.5–3.4 × 0.5–1.3 mm, acute to obtuse, green or with brown patches, midrib green extending beyond glume to a fine mucro.
Similar taxa
Most commonly confused with Isolepis crassiuscula which differs from I. lenticularis in having 3 stamens, and much wider spikelets. The culms in this species are usually yellow-green to glaucous, not grass-green as in I. lenticularis.
Distribution
Indigenous. Cosmopolitan. In New Zealand known from North and South Islands.
Habitat
Slow to fast flowing streams, ponds, tarns or lakes, often found floating amongst other plants such as Machaerina arthrophylla (Nees) Koyama, Isolepis crassiuscula Hook.f., or by itself. In alpine habitats often the only aquatic macrophyte present, and in these habitats it can be found in very fast flowing, well aerated water. Usually forming diffuse, submerged to semi-emergent patches but also rarely found as an emergent in ephemeral wetlands, in which case it forms dense mats.
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 – Declining | Qualifiers: DPR, De, PD, SO
Threats
Threatened throughout New Zealand by the spread of wetland weeds, eutrophication, and wetland drainage. In the North Island virtually confined to the Central Volcanic Plateau, though it was once widespread from Northland to the Manawatu. In the South Island now virtually restricted to the West Coast where it is still locally common.
Detailed taxonomy
Family
Synonyms
Scirpus fluitans L., Eleogiton fluitans (L.) Link, Isolepis fluitans (L.) R.Br.; Isolepis fluitans (L.) R.Br. var. fluitans - all refer to a Northern Hemisphere plant not in New Zealand
Endemic taxon
No
Endemic genus
No
Endemic family
No
Ecology
Flowering
December–March
Fruiting
January–May
Propagation technique
Difficult and should not be removed from the wild.
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
Where To Buy
Not commercially available.
Etymology
isolepis: From the Greek isos (equal) and lepis (scale)
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.
ISOLEN
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, SO, Sp
2012 | Threatened – Nationally Vulnerable | Qualifiers: SO
2009 | Threatened – Nationally Vulnerable | Qualifiers: DP, SO
2004 | Gradual Decline
Referencing and citations
References and further reading
Ito Y, Viljoen J-A, Tanaka N, Yano O, Muasya AM. 2016. Phylogeny of Isolepis (Cyperaceae) revisited: non-monophyletic nature of I. fluitans sensu lato and resurrection of I. lenticularis. Plant Systematics and Evolution 302: 231–238. https://doi.org/10.1007/s00606-015-1253-7.
Johnson AT, Smith HA. 1986. Plant Names Simplified: Their pronunciation, derivation and meaning. Landsman Bookshop Ltd, Buckenhill, UK.
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 (14 April 2006). Description adapted from Moore and 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): Isolepis lenticularis Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/isolepis-lenticularis/ (Date website was queried)