Common name
Tropical Reed

Derivation
Phragmites Adans., Fam. Pl. 2: 34, 559 (1763); from the Greek phragma (a hedge) and -ites (resembling). Name used by Dioscorides for a species whose stems were used for making hedges.

karka- origin obscure, possibly the corruption of an Indian vernacular name referring to its white inflorescence.

Published in
Nom. Bot. 2nd edn, 2: 324 (1841).

Common synonyms
Phragmites vallatoria (Pluk. ex L.) Veldkamp

Habit
Perennial. Rhizomes elongated. Basal leaf sheaths absent. Culms erect, reed-like, 100–1000 cm tall. Leaves cauline. Leaf-sheaths loose. Ligule a fringed membrane. Leaf-blades disarticulating from the sheaths, 20–80 cm long, 10–40 mm wide. Leaf-blade surface scaberulous. Leaf-blade apex attenuate, muticous or pungent, hardened.

Inflorescence
Inflorescence compound, a panicle, bearing juvenile spikelets at emergence, with 200–500 peduncles per sheath. Panicle open, oblong, dense, 30–50 cm long, 10–20 cm wide. Primary panicle branches profusely divided, naked below.

Spikelets
Spikelets solitary. Pedicels filiform. Fertile spikelets many flowered, comprising 3–11 fertile florets, with diminished florets at the apex, cuneate, laterally compressed, 9–14 mm long, breaking up at maturity. Spikelets disarticulating below each fertile floret. Floret callus elongated, 0.5–1 mm long, bearded, obtuse, hairs 3–7 mm long, hairs 50% length of lemma.

Glumes
Glumes persistent, similar to each other and to fertile lemma in texture, gaping. Lower glume elliptic, 3.5–4.5 mm long, 50–60% length of upper glume, membranous, 3–5-nerved. Lower glume apex acute. Upper glume elliptic, 4–6 mm long, 50% of length of adjacent fertile lemma, membranous, 3–5-nerved. Upper glume apex acute.

Florets
Basal sterile florets 1, with palea, persisting on inflorescence. Lemma of lower sterile floret similar to fertile lemma, elliptic, 7.5–12 mm long, 100% of length of spikelet, membranous, 3–7-nerved, acuminate. Fertile lemma lanceolate, 8.5–11 mm long, membranous, 1–3-nerved. Lemma surface glabrous. Lemma apex acuminate, muticous. Palea linear or oblong, 2.5 mm long, 66% of length of lemma, 2-nerved. Palea keels scaberulous. Palea surface glabrous. Apical sterile florets resembling fertile though underdeveloped. Lodicules 2. Anthers 3 (2 in sterile floret), 1.5–2 mm long. Ovary glabrous. Grain with adherent pericarp, 1.1 mm long. Hilum elliptic.

Continental Distribution:
Africa, Temperate Asia, Tropical Asia, Australasia, Pacific.

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

Western Australia: Gardner, Fitzgerald, Hall, Dampier. Northern Territory: Darwin & Gulf, Central Australia South. South Australia: Lake Eyre. Queensland: Burke, Cook, North Kennedy, South Kennedy.

Classification. (GPWG 2001):
Arundinoideae: Arundineae

Notes
Native. Common aquatic reed, growing with the rhizomes in water.