Arundo donax L.
A rhizomatose perennial, with erect, woody, leafy stems up to 6 m tall and 4 cm diameter; usually growing in dense clumps. Leaf blades up to 60 cm long, 6 cm wide, more or less glaucous, flat, hairless with rough margins, distinctly nerved. Ligule very short, ciliate. Inflorescence a dense, oblong panicle 30 to 70 cm long, silky and purplish tinged; with erect branches. Spikelets flattened, 10 to 18 mm long; with 2 to 5 florets. Glumes 11 to 13 mm long, lanceolate, 3 to 5-veined. Lemma of the lower floret 11 to 13 mm long, lanceolate, densely covered on the lower two thirds with silky hairs over 8 mm long.
Local: Fairly common in Gibraltar and found in various places around the Rock, but mainly from North Front, along the East Side, and Europa Flats.
Global: Found throughout the Mediterranean region, and world-wide. Probably introduced from Asia.
Flowers from (August) September, October to November.
Grows near and along water courses, riversides; damp places.