Imperata Pl. Rar. Neap. 2: 26 (1792).
Derivation:. Named in honour of Ferrante Imperato, a Neopolitan botanist of the sixteenth century.
Taxonomic revisions, nomenclatural references:. C.E.Hubbard, Imp. Agric. Bur. 7:1–13 (1944).
Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 535–536 (1878); C.A.Gardner, Flora of Western Australia 1 Gramineae 312–314 (1952); J.W.Vickery, Flora of New South Wales, Gramineae 19: 23–25 (1961); E.E.Henty, Manual Grasses New Guinea 111–112 (1969); M.Lazarides, Tropical Grasses S.E. Asia 49–50 (1980); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 278–279 (1983); J.P.Jessop, Flora of South Australia 4: 1990 (1986); B.K.Simon, Flora of the Kimberley Region 1179 (1992); B.K.Simon, Key to Australian Grasses 125 (1993); S.W.L.Jacobs and C.A.Wall, Flora of New South Wales 4: 432 (1993); N.G. Walsh, Flora of Victoria 2: 618 (1994); D.I.Morris, Student's Flora of Tasmania 4B: 353–354(1994); E.Edgar and H.E.Connor, Flora of New Zealand 5: 604–606 (2000); D.Sharp and B.K.Simon, AusGrass (2002); J.P.Jessop, Grasses of South Australia 523–525 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 283 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (571).
Native. 8 species, from tropical and subtropical regions. 1 species in Australia, WA, NT, SA, Qld, NSW, Vic, and Tas. Also New Guinea, Malesia and New Zealand.
Habit. Perennial, rhizomatous. Leaf blades broad or narrow. Ligule a fringed membrane.
Inflorescence. Inflorescence paniculate (silky, spiciform or loosely contracted, the branches with numerous short racemes), a spike-like panicle, contracted. Spikelet-bearing axes short racemes, with homomorphic spikelets. Internodes densely long-hairy (the hairs silvery).
Spikelets. Spikelets subterete to dorsally compressed, 2 flowered, with 1 fertile floret, paired (unequally), pedicelled, unequally pedicelled in each combination; sessile spikelet with lower incomplete floret. Fertile spikelets falling with glumes (falling entire from their pedicels).
Glumes. Glumes more or less equal, long relative to adjacent lemmas, pointed or blunt, awnless, similar (membranous, with long silvery hairs especially towards the base). Lower glume convex on back, relatively smooth, 5–7 nerved. Upper glume 3–5 nerved.
Florets. Lower incomplete floret(s) male (rarely), or sterile. Lemmas awnless, 0 nerved or 1 nerved, exceeding fertile lemmas (rarely, the latter may even be absent), similar in texture to fertile lemmas, not becoming indurated. Fertile florets 1. Lemmas lanceolate to oblanceolate, reduced, sometimes absent, less firm than glumes (hyaline), not becoming indurated, entire at apex or incised (denticulate), when entire pointed or blunt, muticous, 0–1 nerved, glabrous. Palea relatively long or conspicuous and relatively short or very reduced (broad), apically notched, nerveless. Stamens 1. Grain small. Hilum short. Embryo large.
Kranz Anatomy. C4.
2n = 20, 40, 50, and 60, commonly adventive (I. cylindrica being one of the world's worst weeds).
Habitat. Helophytic, mesophytic, xerophytic. Often in damp or weedy places, some forms of I. cylindrica in coastal sand. Species of open habitats.
Classification. Panicoideae; Andropogoneae.
Notes. A homogeneous group of species allied to Miscanthus, but distinguished by the contracted panicle and deficient floral parts (Clayton and Renvoize, 1986).
Types Species. I. arundinacea Cirillo (nom. illeg.) = I. cylindrica (L.) Raeush.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Gondwanan.