Purua grass, Caldwells clubrush
Scirpus caldwellii Cook.
Vascular – Native
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.
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
Previous conservation statuses
2009 | Not Threatened
2004 | Not Threatened
Indigenous. North Island from the Kaipara Harbour south, and mainly easterly. In the South Island widespread from Nelson to Otago, mainly eastern. Also in Australia.
Coastal to lowland in saltmarshes and other poorly drained saline areas. Sometimes invades pasture abutting tidal streams and estuaries.
Summer-green, bulbous perennial forming mostly densely clumped patches. Rhizome 3-5 mm diameter, horizontal, long-creeping, brown, apices terminated by globose, ligneous tubers. Culms 1(-3) per tuber, 0.3-1.0 m tall, 2-3 mm diameter, triquetrous; basal sheaths 1-2, mostly membranous, with a short channelled lamina. Leaves numerous, culms, 200-320 x 2.5-4.0 mm, double-folded but flattened, grass-like, tapering, coriaceous, margins and midrib scabrid towards apices; sheaths short, closed, coriaceous. Inflorescence a terminal, compact head of 3-6 spikelets; rays if present 1-3, 10-40 mm long, unequal, subtending involucral bracts similar to leaves, > inflorescence, unequal, 40-220 x 1.5-2.5 mm. Spikelets 10-20 mm long, ovoid or cylindric, red-brown. Glumes membranous, pubescent, apices slightly cleft or lacerate, with a scabrid, slightly recurved awn. Hypogynous bristles 6, unequal, about half length of nut, deciduous, red-brown, retrorsely scabrid. Stamens 3. Style-branches 2. Nut 3.5-4.0 x 2.5 mm, biconvex or obovoid, compressed, with a small depression on each side, smooth, apiculate, maturing cream to dull brown and glossy.
Differs from B. fluviatilis (Torr.) Soják and B. medianus (Cook) Soják by the smaller size, often glaucescent leaves, fewer subsessile to very shortly stalked spikelets, consistently 2 style branches, and circular, biconvex nut with distinctly concave (depressed) sides
October - January
December - May
Bristly nuts are dispersed by water and possibly wind (Thorsen et al., 2009).
Easily grown from fresh seed and rooted pieces. Will grow in almost any soil but prefers a sunny, damp soil. Ideal as a pond plant or for planting along tidal streams.
Not Threatened but uncommon in northern part of range
bolboschoenus: From Greek: bolbos (swelling or bulb) and schoinos (rush, reed), from the supposed difference from the genus Schoenus in having bulbous tubers
Where To Buy
Not commercially available
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 2009 Vol. 11 No. 4 pp. 285-309