Tragus Hist. Stirp. Helv. 2: 203 (1768).
Derivation:. From Greek tragos (he-goat), alluding to the similarity of the leaf hairs and spikelet bristles to a goat's beard.
Taxonomic revisions, nomenclatural references:. A.M.Anton, Kew Bull. 36: 55–61 (1981).
Key references (keys and floras):. G.Bentham, Flora Australiensis 7: 459–462 (1878) as Lappago; C.A.Gardner, Flora of Western Australia 1 Gramineae 185 (1952); J.W.Vickery, Flora of New South Wales, Gramineae 19: 305–306 (1975); M.Lazarides, Tropical Grasses S.E. Asia 195–196 (1980); M.Lazarides, Flora of Central Australia 470 (1981); J.C.Tothill and J.B.Hacker, Grasses of Southern Queensland 410–411 (1983); J.P.Jessop, Flora of South Australia 4: 1957–1958 (1986); M.Lazarides, F.Quinn and J.Palmer, Flora of the Kimberley Region 1228 (1992); B.K.Simon, Key to Australian Grasses 170 (1993); S.W.L.Jacobs and S.M.Hastings, Flora of New South Wales 4: 506 (1993); D.Sharp and B.K.Simon, AusGrass (2002); K.Mallet (ed.), Flora of Australia 44B: Poaceae 3: 268–269 (2005); J.P.Jessop, Grasses of South Australia 403 (2006); S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th ed, 386–387 (2008).
W.D.Clayton & S.A.Renvoize, Genera Graminum (1986), genus (434).
Native. 7 species, from tropical Africa with 1 pantropical. 1 species in Australia, WA, NT, SA, Qld, NSW, and Vic.
Habit. Annual or perennial, stoloniferous or decumbent (usually creeping). Leaf blades narrow, slightly cordate or not cordate. Ligule a fringed membrane (very narrow) or a fringe of hairs.
Inflorescence. Inflorescence a false spike, with spikelets on contracted axes (a spicate raceme of crowded glomerules, the latter very shortly- or rarely long- peduncled, each with 2–5 spikelets), a spike-like panicle. Spikelet-bearing axes much reduced (to the glomerules), falling entire (the clusters falling whole).
Spikelets. Spikelets dorsally compressed, 1 flowered, with 1 fertile floret, solitary, sessile to subsessile. Fertile spikelets adaxial (with lower glume against rachis), falling with glumes (in the cluster).
Glumes. Glumes one per spikelet or two, unequal (the lower glume much reduced or absent), (the upper glume) long relative to adjacent lemmas (equalling the spikelet), pointed (acute or acuminate), awnless, non-keeled, dissimilar (the lower tiny, scarious or absent, the upper large, hard, with 5 rows of hooked spines on the back). Lower glume 0 nerved. Upper glume 5–7 nerved, prickly.
Florets. Fertile florets 1. Lemmas lanceolate, acute or acuminate, less firm than glumes (membranous), not becoming indurated, entire at apex, pointed, muticous, 3 nerved, hairy (with minute spinous bristles, all over or only centrally). Palea entire (pointed), 2 nerved. Lodicules 2. Stamens 3. Grain small, compressed dorsiventrally or terete. Hilum short. Embryo large, with one scutellum bundle.
Kranz Anatomy. C4.
2n = 20 and 40, 2 and 4 ploid, commonly adventive.
Habitat. Mesophytic to xerophytic. Often in disturbed ground. Species of open habitats.
Classification. Chloridoideae; Cynodonteae.
Notes. Tragus is defined by the disarticulating inflorescence, the rudimentary first glume and the awnless second glume, which has distinct prickles or spines on its nerves; all these characters are good and constant, and allow an easy recognition of the genus (Anton, 1981).
Types Species. T. racemosus (L.) All.
Biogeographic Element. Clifford & Simon 1981, Simon & Jacobs 1990: Gondwanan.