Lachnagrostis lyallii

Detailed description

Usually large, rather laxly tufted, stoloniferous, perennial grass forming patches 50–150 mm with wide, flat, or narrow and folded, light or dull green leaves, and lax, often rather large panicles in proportion to plant. Sometimes short, densely tufted plants with narrow involute leaves. Branching extravaginal. Leaf-sheath submembranous, distinctly ribbed, smooth or minutely scabrid above, green to creamy brown, sometimes purplish. Ligule 0.6–4.0 mm, ovate-oblong, more or less truncate, denticulate to lacerate, undersides minutely scabrid. Leaf-blade 20–150 × 0.3–6.0 mm, flat or folded, upper surface smooth to finely scabrid on ribs throughout or near apex, undersides finely scabrid on ribs; margins minutely scabrid, apex subacute. Culm 30–450 mm, erect or geniculate at base, longer culms projecting beyond uppermost sheaths, internodes usually finely scabrid below panicle. Panicle 40–250 × 10–160 mm, very lax or sometimes contracted after flowering, with widely spreading, finally horizontal branches; branches rather few, very finely, more or less sparsely scabrid, with 1–2–several spikelets at branchlet tips. Spikelets 2.3–5.0 mm, pale green to light straw-coloured, greenish brown or purplish. Glumes subequal, ovate-elliptic or narrowly elliptic-lanceolate, acute, mid-nerve and hyaline margins scabrid near apex or in upper half. Lemma 1.5–2.8 mm, ½–¾ length of glumes 5-nerved, with numerous to sparse, scattered, short fine hairs, sometimes glabrate, or the upper ⅓ glabrous, elliptic-oblong, truncate, lateral nerves slightly to obviously excurrent; awn 1.7–6.0 mm long, geniculate, more or less mid-dorsal. Palea length about ½ or = to lemma, keels very faint, 0.1–0.2 mm apart, apex truncate, or obtuse, or shallowly notched. Callus hairs moderately dense, to 1 mm long, to ⅓ length of lemma. Rachilla prolongations absent or up to 1 mm long, tipped by a few equally long, or longer hairs. Lodicules 0.7–0.9 mm, linear, acute. Anthers 0.3–1.5 mm. Seed 1.2–2.0 × 0.4–0.8 mm.