Lachnagrostis filiformis

Detailed description

Rather variable, usually slender, upright, tufted, glaucous green, light green to yellow green, annual or short-lived perennial grass up to 700 mm tall; whole plant usually withering early and culms not breaking up below panicle. Branching intravaginal. Leaf-sheath firmly membranous, distinctly ribbed, glabrous below, very finely scabrid above. light green, later light brown. Ligule 1–5 mm, oblong, rounded or tapered, later lacerate, undersides with sparse prickle-teeth. Leaf-blade 25–200 × 1.5–3.0 mm, usually flat, sometimes involute and 0.5–1.0 mm diameter, glabrous, or ribs scabrid; margins very finely scabrid, apex finely acute. Culm 100–350 mm, erect to spreading, internodes usually densely, minutely scabrid, occasionally smooth. Panicle 90–300 × 5–250 mm, yellow green, faintly purple-green drying white, delicate, enclosed at base by the uppermost leaf-sheath, at first contracted, later very lax; branches filiform, numerous, unequal, very finely scabrid, primary branches naked for much of length, with spikelets in clusters of 2-many, towards tips of the much shorter capillary secondary branches. Spikelets 2.5–4.2 mm, pale silvery green to purplish. Glumes subequal, acute to acuminate, usually glabrous, membranous, very narrow linear-lanceolate, lower glume usually slightly longer and more acuminate; keel scabrid. Lemma 1.3–2.3 mm long, one half to two-thirds length of glumes, 5-nerved, moderately covered with very short hairs, oblong-ovate, glabrous near hyaline, truncate, erose apex, lateral nerves very short excurrent; awn 3-6 mm geniculate, more or less mid-dorsal or form c. upper one third. Palea ¾-⅘ length of lemma, keels 0.1 mm apart, apex subobtuse. Callus ringed by minute hairs 0.3–0.4 mm, to one quarter of lemma. Rachilla prolongation absent or 0.3 mm long tipped with hairs to 0.8 mm long. Lodicules 0.5–0.9 mm,linear, acute. Anthers 0.2–0.3 mm. Seed 0.8–1.3 × 0.3–0.5 mm long.