1. Phragmites australis (Cav.) Trin. ex Steud. (common reed)

Pl. 128 c, d; Map 522

P. communis Trin.

P. communis var. berlandieri (E. Fourn.) Fernald

Plants perennial, tall, and reedlike, with stout rhizomes, forming large colonies. Flowering stems 200–400 cm long, stout, unbranched or rarely few‑branched, glabrous, sometimes glaucous. Leaves all on the flowering stems. Leaf sheaths glabrous or sometimes hairy along the margins, the ligules membranous with a hairy margin. Leaf blades 40–60 cm long, 20–40 mm wide, flat, not clasping at the base, roughened along the margin, but otherwise glabrous, the midvein noticeably thickened beneath. Inflorescences large, dense panicles with numerous, ascending branches. Spikelets 10–15 mm long, obovate to obtriangular in outline, somewhat flattened, with 3–7 florets, the lowermost floret staminate or sterile, the rachilla densely long‑hairy between the florets. Lower glume 3–4 mm long, narrowly elliptic, pointed to bluntly pointed at the tip, 3‑nerved, glabrous. Upper glume 6–8 mm long, linear, tapered to a sharply pointed tip, 3‑ or 5‑nerved, glabrous. Lemmas 8–12 mm long, linear, long‑tapered to a sharply pointed tip, 3‑nerved, glabrous. Paleas much shorter than the lemmas. Fruits (seldom produced) 2–3 mm long, oblong in outline, circular or slightly flattened in cross‑section, with a short, stylar beak at the tip. 2n=36, 42, 44, 46, 48, 49, 50, 51, 52, 54, 56, 84. July–September.