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
Vascular – Native
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 Vulnerable | Qualifiers: SO
Previous conservation statuses
2009 | Threatened – Nationally Vulnerable | Qualifiers: DP, SO
2004 | Gradual Decline
Indigenous. Cosmopolitan. In New Zealand known from North and South Islands.
Slow to fast flowing streams, ponds, tarns or lakes, often found floating amongst other plants such as Baumea arthrophylla (Nees) Boeck., 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.
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 x 0.3-1.7 mm, green or brown, lamina 2-80 x 0.2-1.1 mm. Inflorescence terminal, not proliferating; bract 2-12 x 0.3 - 1.3 mm. Spikelet 1, 2.4-9.4 x 0.7-2.7 mm, with 4-28 glumes. Glumes 1.5-3.4 x 0.5-1.3 mm, acute to obtuse, green or with brown patches, midrib green extending beyond glume to a fine mucro
Most commonly confused with I. 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.
December - March
January - May
Difficult and should not be removed from the wild.
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.
isolepis: From the Greek isos (equal) and lepis (scale)
Where To Buy
Not commercially available.
Fact Sheet prepared for NZPCN by P.J. de Lange (14 April 2006). Description adapted from Moore and Edgar (1970)
References and further reading
Ito, Y.; Viljoen, J-A.; Tanaka, N.; Yano, O.; Muasya, A.M. 2015: Phylogeny of Isolepis (Cyperaceae) revisited: non-monophyletic nature of I. fluitans sensu lato and resurrection of I. lenticularis. Plant Systematics and Evolution 301:1-8.
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.
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)