Flora of New Zealand Series

; Holotype: CHR 389251! A. P. Druce Burgoo St[rea]m, N.W. Nelson, 3400 ft, periodically flooded riverflat, March 1982.

Rather slender, perennial tufts, 30-80 cm, usually with narrow leaves and very lax panicles with few branches tipped by few spikelets; branching extravaginal. Leaf-sheath submembranous, with few, distinct ribs, very sparsely, finely scabrid throughout or only above. Ligule 1.2-5-(8) mm, truncate and erose in lower leaves, tapering in upper leaves, abaxially scabrid. Leaf-blade 3-25 cm × 0.4-1.5-(2.5) mm, flat, or folded and ± involute, narrow-linear, abaxially almost smooth near base to closely scabrid near acute tip, adaxially ribbed and scabrid on ribs, margins scabrid. Culm 6-50 cm, ± geniculate at base, internodes minutely retrorsely scabrid above. Panicle 4-30 × 3-20-(30) cm, very lax at maturity, often wider than long; primary branches naked, capillary, finely scabrid, becoming horizontal or reflexed, secondary branchlets much shorter, each tipped by a single spikelet. Spikelets 3-8 mm, light green to purplish. Glumes ± equal, elliptic-lanceolate, scabrid above on keel and near hyaline margin, tip acute to sometimes acuminate. Lemma (2.5)-3-3.8 mm, c. ¾ length of glumes, 5-nerved, with scattered short hairs usually near margins on lower ⅔, or rarely glabrous, elliptic-oblong, truncate, denticulate, lateral nerves usually very shortly excurrent, margins and nerves finely scabrid near apex; awn (0.3)-1-5 mm, usually straight, sometimes curved, arising dorsally from just above midpoint of keel to just below lemma apex, rarely awn 0. Palea c. ½ length of lemma or shorter, keels ± distinct, c. 0.2 mm apart, apex shallowly bifid. Callus hairs to 1 mm, to ⅓ length of lemma. Rachilla prolongation 0.1-0.8 mm, with tuft of hairs to 1 mm; rarely 0. Lodicules 0.6-0.9 mm, linear, acute. Anthers (0.6)-0.8-1.2 mm. Caryopsis 1.5-1.8 × 0.5-0.7 mm.

N.: Urewera National Park, Volcanic Plateau and Mt Egmont; S.: to west of Main Divide and in Fiordland, to the east in scattered localities; St. Usually in damp ground in tussock grassland and open forest; lowland to subalpine.

Endemic.

Lachnagrostis elata resembles taller plants of L. lyallii in being a lax-growing perennial with extravaginal branching. However, panicles in L. elata are more lax, often with fewer branches and spikelets than in L. lyallii and lemmas in L. elata are longer, usually 3-3.8 mm, compared to 2-2.5 mm in L. lyallii.

Rarely spikelets proliferous, e.g., CHR 324489 A. P. Druce L. Cobb, north-west Nelson, Apr 1969.