Eleusine tristachya

3. Eleusine tristachya (Lam.) Lam. (syn.: E. italica Terr., Cynosurus tristachyos Lam.) (S-Am.) – A regular, but usually ephemeral alien. Formerly mainly introduced as a wool alien in the Vesdre valley, at least between 1887 and 1960. Occasionally seen elsewhere, often without obvious vector of introduction (Antwerpen, Brussel, etc.). In more recent times still regularly seen and sometimes persisting for several years, for instance as a roadside weed in the port of Antwerpen (Noorderlaan at Churchilldok, at least between 1992 and 2002 but now gone; see Verloove 2002). Furthermore discovered in 2005 on bare, gravelly soil of a disused railway yard between Gent and Merelbeke (Moskou) and reported as further spreading there in 2009 (by now, in 2013, seemingly firmly established). In the past years also recorded in Roeselare (wasteland) and near Lokeren (E17 motorway).

In addition to the diacritic features given in the key, Eleusine tristachya is readily distinguished from E. coracana (and E. indica) by its lemmas with a more rounded back. Eleusine tristachya is said to be annual by Vivant (1959), Hilu (2003) and others. However, it is evidently perennial but often flowers in the first year. Contrary to Phillips (1972) and Stace (2010) – who both distinguished Eleusine indica and E. tristachya on the basis of lemma characteristics (lemma pointed and obtuse respectively) – E. tristachya often even has more prominently pointed lemmas than E. indica or E. coracana. The presence or absence of ciliae along the margins of the sheaths (see Vivant 1959) neither is a reliable feature although sheaths of Eleusine indica or E. coracana sometimes tend to be more ciliate than those of E. tristachya. Inflorescence branches can reach up to 80 mm according to Hilu (2003) but this is never the case in our area where they reach at most 30 mm.

The exceedingly similar but tropical African Eleusine multiflora Hochst. ex A. Rich. might have been overlooked. It is an annual with usually slightly more acute lemmas and a shortly racemose inflorescence but these features seem fairly variable and often difficult to assess. Both are probably best distinguished on grain characters: these are very finely and densely granular in Eleusine multiflora and coarsely striate in E. tristachya. Eleusine multiflora is a fairly frequent wool alien in the British Isles (Stace 2010) but none of the Belgian collections of E. tristachya seems to pertain to that species.

Eleusine tristachya, Melle (Gent), by railway track, August 2009, W. Vercruysse.

Eleusine tristachya, inflorescence - Drawing S.Bellanger

Herbarium specimen


Hilu K.W. (2003) Eleusine. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 25. Oxford University Press, New York-Oxford: 109-110.

Lambinon J. (1959) Contribution à l’étude de la flore adventice de la Belgique. II. Etude sur diverses Gramineae. Bull. Soc. Roy. Bot. Belg. 91: 179-195.

Phillips S.M. (1972) A survey of the genus Eleusine Gaertn. (Gramineae) in Africa. Kew Bull. 27: 251-270.

Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.

Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.

Verloove F. & Vandenberghe C. (1996) Nieuwe en interessante voederadventieven voor de Belgische flora, hoofdzakelijk in 1995. Dumortiera 66: 11-32.

Vivant J. (1959) L’Eleusine tristachya Kunth, adventice en Gironde. Bull. Soc. Bot. Fr. 106: 28-30.

Wallnöfer B. (2014) Über die Verbreitung von Eleusine indica und E. tristachya (Gramineae) in Österreich. Annalen des Naturhistorischen Museums in Wien, Serie B 116: 181-190.

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