Flora of New Zealand Series

; Holotype: CHR 225566! A. E. Esler 3597 Motuorahi, Coromandel Islands, Hauraki Gulf, coastal rocks, 16.10.1971.

Open tufts to 60 cm, erect or often drooping, with slender pale yellow-green to glaucous leaves and whitish open panicles; branching extravaginal. Leaf-sheath to 6 cm, glabrous, or with fine, very minute prickle-teeth, to minutely puberulous. Collar hairs few, long. Ligule 0.2-0.3 mm, truncate, slightly erose, glabrous, or rarely sparsely minutely ciliate. Leaf-blade 10-20-(30) cm × 0.5-1.5-(4) mm, usually narrow and inrolled, sometimes flat, abaxially smooth or with sparse to dense prickle-teeth towards tip, rarely throughout, adaxially ± shallowly ribbed, sparsely minutely prickle-toothed or sparsely pubescent on ribs; margins minutely prickle-toothed. Culm 6-35 cm, internodes glabrous, occasionally with a few short hairs above basal nodes, sometimes with a few minute prickle-teeth below panicle. Panicle (3)-8-18-(27) × 0.7-3.5-(5) cm, oblong-lanceolate, becoming lax with spreading branches but spikelets clustered and individually inconspicuous; rachis, branches, and pedicels with sparse to dense fine prickle-teeth, or rachis smooth below. Spikelets (4.5)-5-7-(7.5) mm, whitish or pale straw-coloured, sometimes purple-tinged. Glumes unequal, hyaline, keels minutely prickle-toothed in upper ½; lower ⅔-⅘ length of upper, linear-lanceolate, upper slightly < spikelet, elliptic-lanceolate; margins entire, or with a few minute prickle-teeth near acuminate tip. Lemma 4.5-6 mm, bicuspid, papillose; awn 3.5-8 mm, straight to later recurved, insertion in upper ¼ of lemma. Palea with minute prickle-teeth on keels and rarely on margins. Callus hairs to 0.5 mm. Rachilla hairs to 2 mm. Lodicules to 1 mm, glabrous. Anthers 1.2-2 mm. Gynoecium: ovary to 1 mm; stigma-styles to 1.3 mm. Caryopsis c. 2.6 × 0.6 mm.

N.: scattered localities, usually coastal but frequently inland in Waikato and Wellington Province; S.: Marlborough, few records in eastern mountains; Three Kings Is. Coastal and inland on bluffs, usually on calcareous rocks, sometimes on basalt, on serpentinite at North Cape, and near bird roosts on offshore islands in the Hauraki Gulf; 3-800 m. FL Oct-Jan.

Indigenous.

Also indigenous to Norfolk Id.

Trisetum arduanum was collected by Banks and Solander in N.Z. on Cook's first voyage, e.g, WELT 63935, and described in Solander's unpublished MS under the name Avena flavescens. It was formerly more common in the Auckland region but is now collected only occasionally north of Auckland [de Lange, P. J. and Crowcroft, G. M. Auck. Bot. Soc. J. 51: 38-49 (1996)].

Trisetum was not previously recorded for Norfolk Id, see Green, P. S. Fl. Australia 49: 442-499 (1994); T. arduanum was recently collected there, CHR 529149 P. J. de Lange NF 223 Norfolk Id, Mt Pitt National Park, Bridle Track near Cooks Monument, 13.11.1998.