Tragus racemosus (L.) All. (syn.: Cenchrus racemosus L.) (warm temp. Old World) – A very rare and (up to present) ephemeral alien. Already recorded in Belgium – without further details – prior to 1850 (possibly in Gent; see Fasseaux 1949). Between 1887 and 1947 Tragus racemosus was a rather regular wool alien in the valley of river Vesdre (Ensival, Goé, Trooz, etc.). In 2011 discovered in abundance on a railway yard in Melle near Gent, along with (few plants of) Eleusine tristachya (see also: http://waarnemingen.be/waarneming/view/56557995). Here possibly naturalised and present since quite some time. In 2017 few plants were observed in another abandoned railway yard in Gent (Wondelgem).
Tragus racemosus is fast spreading from southern Europe and its (re-) occurrence in Belgium was more or less expected. It has several more or less stable populations in northern France, for instance in the central reservation of motorway A1 north of Paris and on semi-abandoned railway yards in Hénin-Beaumont (between Douai and Lens) and in Aulnoye-Aymeries (pers. obs. author). See also Mouchot (2000) for records in the Lorraine-area.
Ryves & al. (1996) include the East-African Tragus heptaneuron Clayton in T. racemosus but this point of view is not followed by other taxonomists (compare with Anton 1981, Wipff 2003).
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Literature
Anton A.M. (1981) The genus Tragus (Gramineae). Kew Bull. 36: 55-61.
Fasseaux W. (1949) Les Tragus adventices en Belgique. Bull. Soc. Roy. Bot. Belg. 82: 67-70.
Mouchot E. (2000) Découverte de Tragus racemosus en Lorraine. Monde Pl. 468: 11.
Ryves T.B., Clement E.J. & Foster M.C. (1996) Alien grasses of the British Isles. BSBI, London: XX + 181 p.
Wipff J.K. (2003) Tragus. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 25. Oxford University Press, New York-Oxford: 278-281.