Echinochloa polystachya* (H.B.K.) Hitchc. Contr. U.S. Natl. Herb. 22: 135 (1920).
Classification. (GPWG 2001) : Subfamily Panicoideae. Paniceae.
Basionym and/or Replacement Name: Oplismenus polystachyus Kunth, Nov. Gen. Sp. (quarto ed.) 1: 107 (1815 [1816]).
Type of Basionym or Protologue Information: HT: Humboldt & Bonpland s.n., Apr, Venezuela: Amazonas: prope Maypure (P; IT: US-s.n. (fragm. ex P)).
Recent synonyms: Echinochloa praestans.
Key references (books and floras): [2002] D.Sharp & B.K.Simon, AusGrass, Grasses of Australia, [2008] S.W.L.Jacobs, R.D.B.Walley & D.J.B.Wheeler, Grasses of New South Wales (228).
Illustrations: [2008] S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th edn (228).
Habit. Perennial. Culms decumbent, 100–300 cm tall, 7–15 mm diam., spongy. Mid-culm nodes glabrous or pubescent. Lateral branches branched. Leaf-sheaths glabrous on surface or hairy. Ligule a fringe of hairs, 2–4 mm long. Leaf-blades 25–50 cm long, 20–35 mm wide. Leaf-blade surface glabrous.
Inflorescence. Inflorescence compound, a panicle of racemes. Racemes numerous, 2–11 cm long. Central inflorescence axis 15–30 cm long.
Spikelets. Spikelets sessile and pedicelled. Fertile spikelets 2-flowered, the lower floret barren (rarely male), the upper fertile, comprising 1 basal sterile florets, comprising 1 fertile floret(s), without rachilla extension, ovate, dorsally compressed, 4.5–6 mm long.
Glumes. Glumes dissimilar, thinner than fertile lemma. Lower glume ovate, without keels, 5–7 -nerved. Upper glume ovate, membranous, without keels, 5–7 -nerved. Upper glume surface indumented. Upper glume apex muticous or awned. Florets. Basal sterile florets 1, male, with palea. Lemma of lower sterile floret 100 % of length of spikelet, membranous, 5 -nerved, muticous or awned.
Fertile lemma 2.5–5 mm long, without keel. Anthers 3.
Continental Distribution: Australasia, North America, and South America.
Australian Distribution: Introduced from South America, Northern Territory, Queensland.
Northern Territory: Darwin & Gulf. Queensland: Cook, North Kennedy, South Kennedy, Port Curtis.
