Eleocharis pusilla
Synonyms
None - though New Zealand plants have at times been referred to the northern hemisphere Eleocharis acicularis (L.) Roem. et Schult.
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.
ELEPUS
Chromosome number
2n = 30
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 | Not Threatened | Qualifiers: SO
Previous conservation statuses
2009 | Data Deficient | Qualifiers: SO
2004 | Not Threatened
Distribution
Indigenous. In New Zealand known from North and South Islands - often ucnommon over large parts of its range, and showing a decided preference for clean waterways free from pollution. Present in Australia.
Habitat
Usually found on the margins of and submerged within lakes, tarns and slow flowing rivers and streams. When submerged it often grows amongst drifts of quillworts (Isoetes spp.) and is rarely fertile. In emergent situations it is is easily overlooked because it has inconspicuous flowers and can be mistaken for a small tuft of grass.
Features
Emergent or aquatic diminutive, sedge forming bright green (when exposed) or dark green to brown-green tufts. Rhizomes 1-3 mm diameter (usually very slender), pale brown. Culms densely tufted, 10-120 mm long, setaceous, < 0.5 mm diameter, bright green (when exposed), dark green to brown green with yellowish transverse bars when submerged; sheaths membranous, more or less hyaline, red-veined, upper most sheaths colourless and inflated below the oblique orifice. Spikelet 2.5-3.0 x c.1 mm, (1-)5-flowered, ovate, sharply acute. Glumes 1.5-2.0 mm long, ovate, obtuse. Hypogynous bristles mostly absent, rarely 2-3 present. Stamens 3, Style 3-fid. Nut c. 1.0 x 0.5 mm, narrowly obovoid, obscurely trigonous, almost white, each face with 3-4 thick, vertical ribs joined by fine transverse bars; the persistent style very small, much constricted at the base.
Similar taxa
Most likely to be confused with E. gracilis R.Br. from which it differs by the smaller spikelets (up to 3 mm long) and by the nut which has prominent vertical ribs and fine transverse bars. The culms of this species are often bright green, and distinctly tufted so as to resemble a small grass. In submerged plants the culms often have an obvious yellow transverse patterning on the otherwise dark green to bronw-green coloured culms.
Flowering
September - February
Fruiting
November - April
Life cycle
Bristly nuts are dispersed by water and possibly wind and attachment (Thorsen et al., 2009).
Propagation technique
Can be tricky to establish. Does best as a submerged aquarium plant where it can be very attractive. Prefers semi-shade and regular immersion in water.
Threats
Not Threatened - but not very common in the northern part of its range where it is clear, based on herbarium evidence that it has undergone a large decline. Still abundant in the deeper, cleaner and less polluted lake systems of the North Island. Common in the South Island.
Etymology
eleocharis: Charm of the swamp
pusilla: Small
Where To Buy
Not commercially available.
Attribution
Description adapted from Moore and Edgar (1970)
References and further reading
Moore, L.B.; Edgar, E. 1970: Flora of New Zealand. Vol. II. Government Printer, Wellington.
Thorsen, M. J.; Dickinson, K. J. M.; Seddon, P. J. 2009. Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11: 285-309