Flora of New Zealand Series

Australian Sedge

Robust, harsh, dense tussocks 30-90 cm high; tillers intravaginal. Stems ± terete, slender, smooth, drooping. Leaves 3-5 mm wide, ± = stems, harshly scabrid, strongly keeled, Y-shaped in cross-section, bluish-green, almost white at base above the red-brown sheath. Inflorescence a drooping panicle with long-peduncled spikes in fascicles of 3-4 from each node; bracts leaf-like, conspicuous but < inflorescence. Male spike 1, 4-5 cm × c. 1.5 mm, invariably with a few female flowers interspersed, shortly pedunculate; glumes ± oblong, acute to mucronate. Female spikes 1.5-6 cm × 3-4 mm, on filiform drooping peduncles much > spikes, flowers up to 30 in longest spikes, lax; glumes < utricles, 3.5-4.5 mm long, ovate, light brown, keel scabrid, mucro short. Utricles c. 6 × 1.5 mm, distinctly nerved, margins strongly scabrid, trigonous, fusiform beak to 2 mm long, bifid, stipe long, ± 1.5 mm. Stigmas 3. Nut trigonous, obovoid.

N. Fairly common as far south as Waikato; more scattered southwards in Bay of Plenty, East Cape, Gisborne, north Taranaki, Manawatu, Porirua; in poorly developed hill pastures. S. Marlborough -Havelock. (Australia)

First record: Cheeseman 1906: 1089, as C. longifolia R. Br. [1810, antedated by C. longifolia Host 1809].

First collections: Cheeseman' s specimens at AK are undated i.e. St John' s College, Auckland, T.F. Cheeseman (AK 97417-21); an undated specimen at K, "vicinity of Auckland (naturalised) T.F.C. 1664", was determined by C. B. Clarke in November 1902.

The robust and aggressive C. longebrachiata is distinguished from native spp. which are invasive weeds of grassland, by the intravaginal tillers, broad leaves, Y-shaped in section, long-stalked pendent spikes and long-beaked utricles; differing from the closely related Australian C. iynx in the taller, more stiffly erect, denser habit, harsher leaves, Y-shaped (not V-shaped) in section, and male spikes usually solitary.

C. longebrachiata is normally unpalatable and fire-tolerant, occurring as scattered plants, small colonies, or dense extensive communities completely replacing the grassland; established in poorer open grassland and especially troublesome on steeper unploughable hill country.

The Australian Sedge Subsidy Scheme was set up to assist control of this sp., the only sedge in N.Z. classed as a noxious weed. It is troublesome, too, in coastal districts of New South Wales, where it is known as Bergalia tussock or drooping sedge. C. longebrachiata was presumably introduced many times to N.Z. with imported seed, as it occurs mainly in the "paspalum zone" of North Island and may still be found in commercial samples of Australian paspalum seed. Localised infestations of C. longebrachiata occur outside the "paspalum zone" as far south as Marlborough suggesting that it could establish successfully in other districts in both islands.

The increasing importance of C. longebrachiata as a grassland weed has led to the publication of a number of papers on identification, ecology and control measures, e.g. E. N. Honore (N.Z. Weed & pest Control Conf. Proc. 16, 1963, 23-7; Ibid. 19, 1966, 107-9; D. M. E. Merry (N.Z. J. Agric. 114, 1967, 44-7); B. P. J. Molloy & E. Edgar (Ibid. 114,1967,41-4); B. P. J. Molloy, P. J. Rumball & G. L. B. Cumberland (N.Z. Grasslands Assoc. Conf., 1967, Proc. 1968, 112-27); R. W. Moody (N. Z. Weed & Pest Control Conf. Proc. 27, 1974, 135-8); and P. J. Rumball (N.Z. J. Agric 126(2), 1973, 45-6).