Plants perennial, tall, and reedlike, with stout, knotty
rhizomes, forming large colonies. Flowering stems 200–600 cm long, stout,
unbranched or few‑branched, glabrous. Leaves all on the flowering stems.
Leaf sheaths glabrous, the ligules membranous with a minutely hairy margin.
Leaf blades 40–75 cm long, 30–70 mm wide, flat, somewhat 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, with 2–4 florets, obovate to
obtriangular in outline, somewhat flattened, the rachilla glabrous between the
florets. Glumes 8–13 mm long, similar in size and shape, nearly as long as the
spikelet, narrowly lanceolate, tapered to a sharply pointed tip, 3(5)‑nerved,
glabrous. Lemmas 5–10 mm long, lanceolate, wrapped around the palea and fruit,
tapered to a sharply pointed or more commonly short‑awned tip, 3‑
or 5‑nerved, densely long‑hairy in the basal half. Paleas shorter
than the lemmas. Fruits not produced (narrowly oblong elsewhere). 2n=110.
September–November.
Introduced, uncommon, and widely scattered in Missouri (native of southern Europe, southern Asia, and northern Africa; escaped from
cultivation in the southern U.S.). Open, disturbed areas.
Giant reed is cultivated as an ornamental and sometimes
escapes when rhizome pieces are dispersed by water or discarded by humans. Once
established, it can form large, dense colonies but does not appear to be
invasive in natural communities in Missouri. In its native range, this species
is used for building materials (both stems and leaves), woven mats, and pulp
for paper. The reeds of woodwind instruments are cut from its stems. For
discussion of differences with the superficially similar giant cane (Arundinaria
gigantea (Walter) Muhl., tribe Bambuseae), see the treatment of that
species.