Isolepis crassiuscula
Synonyms
Scirpus crassiuscula (Hook.f.) Benth., Scirpus crassiusculus
Family
Cyperaceae
Flora category
Vascular – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Sedges
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.
ISOCRA
Chromosome number
2n = c.64
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) – more information about this can be found on the NZTCS website. This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants.
Please note, threat classifications are often suggested by authors when publications fall between NZTCS assessment periods – an interim threat classification status has not been assessed by the NZTCS panel.
- Conservation status of New Zealand indigenous vascular plants, 2017 . 2018. 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. 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: RR, SO
Previous conservation statuses
2012 | At Risk – Naturally Uncommon | Qualifiers: RR, SO
2009 | At Risk – Naturally Uncommon | Qualifiers: SO
2004 | Range Restricted
Distribution
.Indigenous. North Island, Central Volcanic Plateau from the upper Rangitoto Range and Kaingaroa Plain south to the northern Ruahine Range and Waiouru area. Also present in Australia and New Guinea
Habitat
An upper montane – alpine (700–1500 m a.s.l.) sedge of bogs, mires, pond, tarn and stream margins. Sometimes found wholly aquatic in deep pools, ponds or slow flowing streams.
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).
Detailed description
A densely tufted yellow-green to glaucous green sedge. Terrestrial plants rather dense, more or less compact tufts 60–150 mm diameter, aquatic forms forming floating mats up to 1 m long in slow flowing water. Rhizome much elongated, branched and rooting at nodes. Culms 20–200 × 1–2 mm, usually rather rigid, less so in aquatic plants, erect, very leafy. Leaves 40–60 × 1–1.5–(2) mm, ≤ or > than culms, narrow-linear, lamina flattened, apex subobtuse; lowermost leaf on branch bract-like with pale membranous sheath up to 6 mm wide. Inflorescence a very stout, solitary, pale-green, flecked with red, terminal spikelet (rarely 2 spikelets), subtending bract absent. Spikelets 3–10 × 2–8 mm, usually rather squat, ovoid or oblong (more usually in aquatic or partially submerged plants). Glumes 2–4 mm, broadly ovate, obtuse, finely nerved, centrally green otherwise red-purple to very dark red-purple towards margins, margibns often a well marked as a wide hyaline band. Hypogynous bristles 0. Stamens 3. Style-branches 2. Nut 1.5 × 1 mm, grey, obovate, compressed, margins distinctly thickened, minutely apiculate.
Similar taxa
A very distinctive sedge which is well marked from the other New Zealand Isolepis by its very thick set, leafy and very chunky yellow-green to glaucous green culms, and rather squat, ovoid, usually solitary terminal spikes. However, aquatic forms can be confused with I. lenticularis R.Br. From that species, I. crassiuscula can be recognised by having 3 rather than 2 stamens, and spikelets which are 2–8 rather than 1–2 mm wide. The spikes of Isolepis lenticularis always have a subtending bract, which is absent in I. crassiuscula.
Flowering
November–March
Fruiting
November–April–(May)
Life cycle
Nuts are dispersed by water and possibly granivory and attachment (Thorsen et al., 2009).
Propagation technique
Easily grown from rooted pieces and fresh seed. Should be planted in a permanently damp, peaty soil, or in a pot kept partially submerged. May be grown under water, and might be ideal as a fish tank plant or pond weed for an outdoor water feature.
Threats
A rather widespread species which can be locally abundant in parts of its central North Island range. It does not seem to be as vulnerable to weed species, such as Juncus bulbosus L. as some other wetland plants of this region (e.g., Schoenus fluitans Hook.f., Isolepis lenticularis R.Br.), and it may in fact not qualify for a conservation assessment in future listings.
Etymology
isolepis: From the Greek isos (equal) and lepis (scale)
Where To Buy
Not commercially available.
Attribution
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.
References and further reading
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.
Thorsen MJ, Dickinson KJM, Seddon PJ. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285–309.