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Piptatherum

Piptatherum* Ess. Agrostogr. 17, 173 (1812).

Derivation:. From the Greek pipto (to fall) and ather (spike) as of ear of wheat, alluding to the awns dropping readily from the lemmas.

Syn: Oryzopsis Michx.

Key references (keys and floras):. C.A.Gardner, Flora of Western Australia 1 Gramineae 183 (1952) as Oryzopsis; J.P.Jessop, Flora of South Australia 4: 1839 (1986); B.K.Simon, Key to Australian Grasses 145 (1993); S.W.L.Jacobs and J.Everett, Flora of New South Wales 4: 637–638 (1993); N.G.Walsh, Flora of Victoria 2: 399 (1994); D.I.Morris, Student's Flora of Tasmania 4B: 194 (1994); E.Edgar and H.E.Connor, Flora of New Zealand 5: 83–84 (2000); D.Sharp and B.K.Simon, AusGrass (2002); J.P.Jessop, Grasses of South Australia 110–111 (2006); J.P.Jessop, Grasses of South Australia 110–111 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 341–342 (2008); A.Wilson (ed.), Flora of Australia 44A: Poaceae 2: 67–68 (2009).

W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (syn. of Oryzopsis).

Naturalised. 25 species or 26 species, from Old World subtropics, North America. 1 species in Australia, WA, SA, NSW, Vic, and Tas. Also New Zealand.

Habit. Perennial, densely or loosely tufted. Leaf blades broad to narrow. Ligule an unfringed membrane.

Inflorescence. Inflorescence paniculate.

Spikelets. Spikelets dorsally compressed (dorsally compressed to subterete), usually long pedicelled; with rachilla terminating in a floret. Fertile spikelets subterete to dorsally compressed, disarticulating above glumes.

Glumes. Glumes more or less equal (subequal), about equal to spikelet or exceeding florets, long relative to adjacent lemmas, pointed, awnless, non-keeled, similar. Lower glume 3–5 nerved (-7). Upper glume 3–7 nerved.

Florets. Fertile florets 1. Lemmas involute (the palea back exposed), decidedly firmer than glumes, becoming indurated, brown in fruit or black in fruit (usually dark brown to black and shiny, brown in P. miliaceum), inconspicuously incised or entire at apex, awned, 3–5 nerved (rarely more?), having margins tucked into palea, not keeled. Awns 1 (fine), from a sinus or apical (when lemma lobes absent), non-geniculate, usually straight (erect, neither twisted nor curved), hairless (scabrous), much shorter than body of lemma to much longer than body of lemma, deciduous. Palea relatively long (equalling the lemma), textured like lemma, indurated (except marginally), 2 nerved, not keeled, glabrous to hairy. Callus short (0.1–0.3 mm long, mostly incurved). Lodicules 3. Stamens 3. Stigmas 2. Grain small to medium sized (1.5–4.0 mm long), compressed dorsiventrally. Hilum long-linear. Embryo large to small (usually about a third of the grain length). Endosperm hard.

Kranz Anatomy. C3.

2n = 24, 2 ploid, commonly adventive.

Habitat. Mesophytic to xerophytic.

Classification. Pooideae; Stipeae.

Types Species. P. coerulescens (Desf.) P.Beauv.

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

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