Common name
Giant Reed
Danubian Reed
Spanish Reed

Derivation
Arundo L., Sp. Pl. 81 (1753); from the Latin arundo, a reed.

donax- the Greek word for a type of reed in classical literature, alluding to the easy dispersal of diaspores by the wind.

Published in
Sp. Pl. 81 (1753).

Habit
Perennial. Rhizomes elongated. Culms erect, reed-like, 200–800 cm tall, 0.5 mm diam. Mid-culm internodes hollow, thin-walled. Leaves cauline. Leaf-sheath auricles present. Ligule a fringed membrane. Leaf-blades drooping, 5–100 cm long, 10–80 mm wide. Leaf-blade surface smooth, glabrous. Leaf-blade apex attenuate. Bisexual.

Inflorescence
Inflorescence compound, a panicle. Panicle open or contracted, oblong, 30–60 cm long. Primary panicle branches profusely divided. Panicle branches scaberulous.

Spikelets
Spikelets solitary. Fertile spikelets many flowered, comprising 2–7 fertile florets, with a barren rhachilla extension, cuneate, laterally compressed, 8–15 mm long, breaking up at maturity. Spikelets disarticulating below each fertile floret. Floret callus evident, pilose, obtuse.

Glumes
Glumes persistent, similar to each other and to fertile lemma in texture. Lower glume lanceolate, 11–13 mm long, equalling upper glume, membranous, 1-keeled, 3–5-nerved. Lower glume apex acute, muticous. Upper glume lanceolate, 125% of length of adjacent fertile lemma, membranous, 1-keeled, 3–5-nerved. Upper glume apex acute, muticous.

Florets
Fertile lemma lanceolate, 6–12 mm long, membranous, 3–9-nerved. Lemma surface villous. Lemma hairs 5–8 mm long. Lemma apex acute or acuminate, muticous or mucronate or awned. Median (principal) awn 1–3 mm long overall. Palea linear or oblong, 4.5–5.5 mm long, 50–70% of length of lemma, 2-nerved. Palea keels ciliolate. Palea surface villous. Lodicules 2. Anthers 3, 2.5–3 mm long. Ovary glabrous. Grain with adherent pericarp, ovoid, 2 mm long. Embryo 100% of length of grain. Hilum punctiform.

Continental Distribution:
Europe, Africa, Temperate Asia, Tropical Asia, Australasia, Pacific, North America, South America.

Australian Distribution:
Western Australia, Northern Territory, South Australia, Queensland, New South Wales.

Western Australia: Dampier, Drummond, Dale, Menzies, Warren. Northern Territory: Central Australia North. South Australia: Eastern, Yorke Peninsula, Southern Lofty. Queensland: Cook, North Kennedy, Mitchell, Port Curtis, Burnett, Darling Downs, Moreton. New South Wales: North Coast, Central Coast, North-Western Slopes, South-Western Plains, North Far Western Plains, South Far Western Plains.

Classification. (GPWG 2001):
Arundinoideae: Arundineae

Notes
Introduced from the Mediterranean, widespread in Australia, disturbed sites, often along stream or canal banks. Flowers March to July.

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