Flora of New Zealand Series

; Holotype: CHR 132825! A. P. Druce Park V[alley] cirque, Tararua Ra, watercourse, Jan. 1965.

Bright green perennial tufts 5-25 cm, with culms overtopping leaves, occasionally stoloniferous; branching intravaginal. Leaf-sheath hyaline, light green to light brown, prominently ribbed, usually smooth, rarely with sparse prickle-teeth. Ligule 1-4.5 mm, truncate to obtuse, denticulate or entire, glabrous. Leaf-blade 2-7 cm × 1.5-2 mm, flat, or folded and c. 0.5 mm diam., abaxially smooth, rarely uppermost leaf scabrid, adaxially prominently ribbed, ribs usually scabrid; margins often entirely smooth, sometimes sparsely, or rarely densely, minutely scabrid, tip fine, blunt, scabrid. Culm erect, internodes glabrous. Panicle (1.5)-2-6 cm, open, laxly oblong to pyramidal, with spreading sometimes flexuous branches; rachis smooth, branches and pedicels smooth or scabrid. Spikelets 2-2.5-(3) mm, usually purplish. Glumes ± unequal, acute to acuminate, keel finely scabrid near tip, margins smooth, rarely scabrid at tip; lower = spikelet, ovate-lanceolate, upper 1.7-2.5-(2.9) mm, elliptic-lanceolate. Lemma 1.5-2 mm, glabrous, faintly 5-nerved, ovate, obtuse; awn (1.5)-2-3 mm, usually middorsal, usually geniculate, sometimes ± straight, slightly projecting beyond glumes. Palea c. 0.5 mm, ovate. Lodicules c. 0.3 mm. Callus with minute hairs. Anthers (0.4)-0.6-0.9 mm. Caryopsis c. 1.5 × 0.7 mm.

N.: Raukumara, Ruahine, and Tararua Ranges; S.: north-west Nelson at Lake Aorere and Mt Domett. Tussock grassland, often in water-courses and seepages, and on rocky ground, cliffs, screes, river flats, usually in shade; subalpine to alpine.

Endemic.

Specimens from north-west Nelson have narrow glumes and small anthers, 0.4-0.5 mm.

Agrostis oresbia resembles A. magellanica in the consistently awned lemmas but is smaller in all respects with a laxer panicle. It seems nearest to A. muelleriana especially in the size and colour of the spikelets, but again A. oresbia has a more lax panicle, and the glumes are less scabrid and less papillose than in A. muelleriana.