Flora of New Zealand Series

; Holotype: CHR 395485! A. P. Druce nr. Skeleton Lakes, Garvie Mts, 4900 ft, bog, March 1988.

Rather lax, perennial tufts, 9-35 cm; branching extravaginal. Leaf-sheath firmly membranous, inconspicuously ribbed, glabrous, light green to dull brown. Ligule 1-2.5 mm, truncate, erose or denticulate, abaxially sparsely, finely scabrid. Leaf-blade 3-10-(15) cm × 1-2 mm, flat or folded, abaxially smooth, adaxially sparsely, finely scabrid on ribs; margins minutely, sparsely scabrid, tip obtuse. Culm 4-20 cm, often included within uppermost leaf-sheath, internodes finely scabrid below nodes and below panicle. Panicle 3-14 × 1.5-8 cm, rather contracted at first, later lax; rachis finely scabrid, branches filiform, finely scabrid, tipped by rather few spikelets. Spikelets (2.5)-3-3.5-(4) mm, pale green or tinged faint purple. Glumes ± equal, elliptic-lanceolate, midnerve and margins scabrid in upper ¼, occasionally in upper ½ or ⅔. Lemma 2-2.5 mm, c. ¾ length of glumes, with scattered soft hairs, very rarely glabrous, ovate-oblong, truncate, lateral nerves not, or scarcely, excurrent, midnerve produced to a mucro, or sometimes a straight subapical awn, to 2.5 mm. Palea ½-⅔ length of lemma, apex shallowly bifid, keels c. 0.3 mm apart, very faint. Callus hairs conspicuous, to 1 mm, to ½ length of lemma. Rachilla prolongation c. 0.2 mm, tipped by hairs to c. 0.8 mm. Lodicules 0.5-0.8 mm, lanceolate, acute. Anthers 0.7-1.3 mm. Caryopsis 1.2-1.8 × 0.5-0.6 mm.

S.: south-western Canterbury (lower Godley River valley), Central and western Otago, Southland (Eyre Mts, Garvie Mts). In seepages, creek margins and boggy ground; subalpine to alpine.

Endemic.

Two-flowered spikelets are occasionally found in plants of Lachnagrostis. Many 2-flowered spikelets were present in panicles of L. uda, OTA 43900 K. J. M. Dickinson & B. D. Rance Leithen Burn headwaters, Black Umbrella Range, 31.1.1986.

Lachnagrostis uda appears close to both L. striata and L. lyallii; L. uda matches L. striata in the short, straight awns, but has much longer anthers, 0.7-1.3 mm, compared to 0.2-0.5 mm in L. striata; L. uda matches L. lyallii in anther length, but the straight awns of L. uda are much shorter (to 2.5 mm), than the geniculate awns of L. lyallii (2-6 mm). In its preference for a very damp habitat L. uda resembles L. striata rather than L. lyallii.