Deyeuxia Ess. Agrost. 43 (1812).
Derivation:. Named for Nicolas Deyeux (1753–1837), professor of pharmacy, University of Paris.
Taxonomic revisions, nomenclatural references:. J.W.Vickery, Contr. N.S.W. Natl. Herb. 1: 574–582 (1940).
Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 577–584 (1878); C.A.Gardner, Flora of Western Australia 1 Gramineae 156–158 (1952); E.E.Henty, Manual Grasses New Guinea 63, 66–67 (1969); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 184–185 (1983); J.P.Jessop, Flora of South Australia 4: 1919–1920 (1986); B.K.Simon, Key to Australian Grasses 95–98 (1993); S.W.L.Jacobs and S.M.Hastings, Flora of New South Wales 4: 548–557 (1993); N.G.Walsh, Flora of Victoria 2: 476–488(1994); D.I.Morris, Student's Flora of Tasmania 4B: 264–273 (1994); E.Edgar and H.E.Connor, Flora of New Zealand 5: 247–254 (2000); D.Sharp and B.K.Simon, AusGrass (2002); J.P.Jessop, Grasses of South Australia 211–214 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th Ed, 196–206 (2008); A.Wilson (ed.), Flora of Australia 44A: Poaceae 2: 190–212 (2009)
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (syn. of Calmagrostis).
Native. About 110 species, from temperate regions. About 35 species in Australia, WA, SA, Qld, NSW, Vic, and Tas. Also New Guinea, Malesia and New Zealand.
Habit. Perennial, tufted. Leaf blades narrow. Ligule an unfringed membrane.
Inflorescence. Inflorescence paniculate, a spike-like panicle or an open panicle with branches ending in single spikelets, open or contracted.
Spikelets. Spikelets laterally compressed, 1 flowered, with 1 fertile floret, awned (usually shortly) or unawned, solitary, pedicelled; with naked rachilla extension, or with rachilla terminating in a floret (rarely). Fertile spikelets disarticulating above glumes.
Glumes. Glumes more or less equal, about equal to spikelet to exceeding florets, long relative to adjacent lemmas (but the lemma usually 3/4 as long, by contrast with Calamagrostis), pointed or blunt, awnless, keeled, similar. Lower glume 1 nerved. Upper glume 1 nerved.
Florets. Fertile florets 1. Lemmas decidedly firmer than glumes (the main, equivocal distinction from Agrostis), not becoming indurated, incised, nearly always awned (rarely only mucronate), 4–5 nerved, glabrous. Awns when present 1, dorsal, non-geniculate or geniculate, much shorter than body of lemma to about as long as body of lemma, deciduous or persistent. Palea relatively long or conspicuous and relatively short or very reduced, 2 nerved. Lodicules 2. Stamens 3. Grain small, longitudinally grooved, with hairs confined to a terminal tuft. Hilum short. Embryo small.
Kranz Anatomy. C3.
2n = 28.
Classification. Pooideae; Poeae.
Notes. Placed in synonymy with Calamagrostis by Clayton and Renvoize, 1986 - " the characters supposedly separating Calamagrostis (lemma hyaline, 1/2 – 2/3 as long as glumes, callus hairs 1/2 to much exceeding lemma) and Deyeuxia (lemma indurated, at least 3/4 length of glumes , callus hairs shorter than lemma) fail so often that the distinction is untenable at generic rank".
Types Species. D. montana (Gaudin) P.Beauv., nom.illeg..
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: IM-NZ-SAm.