Poa annua L.

Loosely to compactly tufted, usually bright green annual, to 35 cm, or short-lived perennial; branching intravaginal; leaf-blades persistent. Leaf-sheath pale green, hyaline, glabrous, keeled. Ligule 0.5–2 mm, entire, rounded, glabrous throughout. Leaf-blade 1.5–9 cm × 3–4 mm, flat or folded, soft, glabrous, often crinkled when young; margins sparsely, minutely scabrid, tip rounded to blunt point. Culm 3–20 cm, erect, spreading or prostrate, internodes glabrous. Panicle 2–10 cm, usually open, erect; branches smooth to sparsely scabrid, spreading to deflexed after anthesis. Spikelets 4–6 mm, with 3–6 crowded florets, light green or sometimes purplish. Glumes ± unequal, glabrous; lower 1.5–2.5 mm, 1-nerved, lanceolate to ovate, acute, upper 2–3 mm, 3-nerved, elliptic to oblong, subobtuse. Lemma 3–3.5 mm, 5-nerved, nerves densely hairy for about ½ length and glabrous above hairs, internerves glabrous, rarely lemma entirely glabrous, purplish just below hyaline band at obtuse tip. Palea 2.5–3 mm, keels long-ciliate, or rarely glabrous, interkeel glabrous. Callus glabrous. Rachilla 0.5–1 mm, glabrous; prolongation much shorter. Lodicules 0.3 mm. Gynomonoecious: each spikelet with 2–3 lower flowers ☿, anthers (0.6)–0.7–1 mm, gynoecium 1–1.5 mm; upper flowers ♀, pollen-sterile anthers to 0.2 mm or 0, gynoecium c. 1.5 mm. Caryopsis c. 1.5 × 0.5 mm, tightly enclosed by anthoecium.

[From: Edgar and Connor (2000) Flora of New Zealand. Volume 5 (second printing).]