Isolepis cernua (Vahl) Roem. & Schult.

Nodding Club-rush

Syst. Veg. 2: 106 (1817) APNI

Taxonomic status:Accepted

Occurrence status:Present

Establishment means:Native

Small tufted or clump-forming, rhizomatous perennial. Culms filiform, 2–20 cm high. Leaves reduced, or rarely blade to 4 cm long. Spikelet 1(–3), 2–6 mm long; involucral bract usually shortly exceeding spikelets, to 1 cm long; glumes obtuse, with sides ± conspicuously 2–6-nerved, straw-coloured to orange- or red-brown, 1–2 mm long; stamens 3; style 2- or 3-fid, sometimes a mixture on one plant. Nut unequally trigonous with the third angle usually obvious or sometimes slightly rounded, obovoid to broad-ellipsoid or broad-obovoid, with a minutely reticulate pattern of slightly raised glistening cells, yellow-brown, dark grey-brown to mid brown, from one-half to two-thirds as long as glume, 0.8–1 mm long, 0.5–0.8 mm diam. Flowers spring–summer.

Brid, CVU, DunT, EGL, EGU, GipP, Glep, Gold, GGr, HNF, HSF, LoM, MonT, MuM, NIS, OtP, OtR, SnM, Strz, VAlp, VRiv, VVP, WaP, WPro, Wim. Also WA, SA, Qld, NSW, ACT, Tas. Widespread, chiefly in cooler southern areas, often near the coast, but with disjunct occurrences at Wyperfeld National Park in the north-west and a few sites in the subalps (e.g. Baw Baws, Wulgulmerang area), usually in permanently moist sites, often somewhat brackish to subsaline.

A variable species that includes several forms over its world range. A distinctive form with broad culms, and with mostly at least 3 spikelets is apparently restricted to coastal sands. This entity appears to match the syntype of Scirpus arenarius Benth. (1878) nom.illeg., which is a replaced synonym of Scirpus psammophilus S.T.Blake. Muasya & Simpson (2002) treated S. psammophilus as a taxonomic synonym of Isolepis cernua var. setiformis (Benth.) Muasya, which however has a 2-fid style (3-fid in S. arenarius). Bentham described S. arenarius as having 2-fid styles, and it is so figured by Clarke (III. Cyper. tab. xlvii. figs. 1-2), however, Blake (1940) points out that the syntypes (from Wilson's Promontory) have 3-fid styles, though otherwise agreeing with Clarke's figure. Another entity with predominantly 2-fid styles may be referrable to Isolepis setiformis (S.T.Blake) K.L.Wilson. Blake explicitly described Scirpus setiformis as a new species, and did not base it on Bentham's variety. In Muasya & Simpson (2002), I. setiformis is distinguished from I. cernua by the number of style branches, with 2-fid styles in I. setiformis 2-fid and  3-fid styles in I. cernua. However, it is currently unclear if this character is reliable, as plants with a mixture of 2-fid and 3-fid styles have been collected.

Close to Isolepis platycarpa (see note for that species).

Source: Wilson, K.L. (1994). Cyperaceae. In: Walsh, N.G.; Entwisle, T.J. (eds), Flora of Victoria Vol. 2, Ferns and Allied Plants, Conifers and Monocotyledons. Inkata Press, Melbourne.
Updated by: Val Stajsic, 2017-11-14

Blake, S.T. (1940). Notes on Australian Cyperaceae 4, Proc. Roy. Soc. Queensland 51: 177-182.

Muasya, A.M. & Simpson, D.A. (2002). A monograph of the genus Isolepis R.Br. (Cyperaceae), Kew Bulletin 57: 257-362.

Hero image
Distribution map
life Life
kingdom Plantae
phylum Tracheophyta
superorder Lilianae
order Poales
family Cyperaceae
genus Isolepis
Higher taxa


Source: AVH (2014). Australia's Virtual Herbarium, Council of Heads of Australasian Herbaria, <>. Find Isolepis cernua in AVH ; Victorian Biodiversity Atlas, © The State of Victoria, Department of Environment and Primary Industries (published Dec. 2014) Find Isolepis cernua in Victorian Biodiversity Atlas
  Bioregion Occurrence status Establishment means
Lowan Mallee present native
Murray Mallee present native
Wimmera present native
Glenelg Plain present native
Bridgewater present native
Victorian Volcanic Plain present native
Victorian Riverina present native
Gippsland Plain present native
Otway Plain present native
Warrnambool Plain present native
Goldfields present native
Central Victorian Uplands present native
Greater Grampians present native
Dundas Tablelands present native
Northern Inland Slopes present native
East Gippsland Lowlands present native
East Gippsland Uplands present native
Wilsons Promontory present native
Highlands-Southern Fall present native
Highlands-Northern Fall present native
Otway Ranges present native
Strzelecki Ranges present native
Monaro Tablelands present native
Victorian Alps present native
Snowy Mountains present native

State distribution

Distribution map
Western Australia
South Australia
New South Wales
Australian Capital Territory