Phalaris arundinacea L.

Robust perennials, 60–200 cm, with long-creeping rhizomes. Leaf-sheath chartaceous, glabrous, striate, light brown. Ligule 2.5–7.5–(10) mm, entire, but soon lacerate. Leaf-blade 20–40 cm × 8–20 mm, ribs numerous, fine, adaxially smooth but scabrid near tip, abaxially with strong midrib near base, ribs densely, minutely scabrid; margins minutely scabrid, long-narrowed to scabrid, acute tip. Culm 50–180 cm. Panicle 9–30 × 1.5–4 cm, lanceolate or oblong, lobed below; rachis smooth below, scabrid above, branches scabrid, spreading at anthesis. Spikelets 4–5.5 mm, pale green or purplish. Glumes ± equal, 3-nerved, lanceolate, keeled but not winged, acute to acuminate, minutely scabrid, rarely lower glume with minute hairs near margin. Ø florets: lemmas equal, 1.3–1.6 mm, narrow, short-hairy. ☿ floret: lemma 3–4 mm, broadly keeled, lanceolate, acute, firm and shining below, short-hairy above; palea much narrower than lemma; anthers (2)–2.5–3.2 mm; caryopsis c. 2 × 1 mm.

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