Oryza Sp. Pl. 333 (1753).

Derivation:. Classical Greek name for rice (Oryza).

Taxonomic revisions, nomenclatural references:. H.Duistermaat, Blumea 32:157–193 (1987); B.Lu, E.B.Naredo, B.J.Amita and M.T.Jackson, Grasses, Systematics and Evolution 51–58 (2000).

Key references (keys and floras):. G.Bentham, Flora Australiensis 7:5 49–550 (1878); C.A.Gardner, Flora of Western Australia 1 Gramineae 14 (1952); E.E.Henty, Manual Grasses New Guinea 133. 136–137 (1969); M.Lazarides, Tropical Grasses S.E. Asia 183–184 (1980); E.M.Bennett, Flora of the Kimberley Region 1194 (1992); B.K.Simon, Key to Australian Grasses 134 (1993); S.W.L.Jacobs and K.L.McClay, Flora of New South Wales 4: 651–652 (1993); D.Sharp and B.K.Simon, AusGrass (2002); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 309–310 (2008); A.Wilson (ed.), Flora of Australia 44A: Poaceae 2: 361–368 (2009).

W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (76).

Native and naturalised. 22 species, from tropical regions. 5 species in Australia, WA, NT, Qld, and NSW. Also New Guinea and Malesia.

Habit. Annual or perennial, rhizomatous or tufted. Leaf blades broad or narrow. Ligule an unfringed membrane.

Inflorescence. Inflorescence paniculate (axes usually wavy, the spikelets appressed) or of spicate main branches (the primary branches often reduced to racemes), an open panicle with branches ending in single spikelets or a racemose panicle with spikelets all similar, open.

Spikelets. Spikelets more than 2 flowered (with 3 florets, the 2 proximal ones sterile), with 1 fertile floret, solitary, pedicelled. Fertile spikelets unconventional (disarticulating above a cupuliform pedicel apex, which is taken to represent glumes, so that the organ serving as a palea may really be a lemma), with lower incomplete floret(s), strongly laterally compressed, disarticulating above glumes (i.e. above the pedicel cup representing them) or i.e. the floret not stipitate.

Glumes. Glumes present to absent (represented only by a small 2-lobed cupule), if present two, minute, more or less equal, shorter than adjacent lemmas, awnless. Lower glume 0 nerved. Upper glume 0 nerved.

Florets. Lower incomplete floret(s) sterile. Lemmas awnless, exceeded by fertile lemmas (usually between 1/8 and 1/2 the length of the spikelet). Fertile florets 1. Lemmas becoming indurated to not becoming indurated (leathery to indurated), entire at apex, pointed, muticous or mucronate or awned, 3–9 nerved, hairy (hispid-ciliate on the nerves) or glabrous (glabrous), strongly 1 keeled. Awns when present, 1, apical, non-geniculate, much shorter than body of lemma to much longer than body of lemma. Palea relatively long (but narrower than the lemma), tightly clasped by lemma (along the lateral nerves), entire (mucronate to subulate), awnless, without apical setae or with apical setae or awned (sometimes with an apical awn or seta), textured like lemma, several nerved, one keeled. Lodicules 2. Stamens 6. Grain small or medium sized or large, compressed laterally. Hilum long-linear. Embryo small.

Kranz Anatomy. C3.

2n = 24 and 48, 2 and 4 ploid, commonly adventive.

Habitat. Hydrophytic, helophytic. Shade species, or species of open habitats.

Classification. Ehrhartoideae; Oryzeae.

Notes. Oryza includes 22 species widely distributed throughout the tropics. Because of considerable morphological variability, the frequent occurrence of intermediate types between some species, and the wide distribution of Oryza species, the taxonomy has long been a problem, particularly in the Orza sativa complex, in terms of species delimitation and nomenclature (Lu et al., 2000).

Types Species. O. sativa L.

Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Gondwanan.

AVH 2011

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith