1. Echinochloa colona (L.) Link (trop.) – A regular but usually ephemeral alien. Probably first collected in the port of Antwerpen in 1889. Formerly very rarely seen as a wool alien in the valley of river Vesdre. However, Echinochloa colona is by far mostly associated with cereals (see for instance Verloove & Vandenberghe 1994). As such it is seen nowadays on unloading quays, under conveyors, wasteland near mills, by roadsides, etc. Records on dumps or in urban areas are probably referable to birdseed waste. In 2005, for instance, it was found in abundance as an urban weed in Gent (foot of wall) and confirmed in the very same place in 2013. In this locality Echinochloa colona survived several consecutive severe winters and seems more or less established.
Typical plants of Echinochloa colona are readily distinguished: the small and always unawned spikelets are neatly arranged in rows, its leaves are narrow (rarely more than 5 mm wide), inflorescence branches lack bristles, etc. However, a particular form of Echinochloa crus-galli (var. praticola; see there) is much alike and both have been intermixed in Belgium. The latter shares the regularly arranged and small spikelets with Echinochloa colona but it has wider leaves, a shorter lower glume, a brownish caryopsis and few or numerous bristles on the inflorescence branches. It usually also is a coarser plant.
There has been much confusion about the correct spelling of the epitheton (see for instance Ward 2005 and Michael 2009 for recent discussions).
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Literature:
Michael P.W. (2009) Echinochloa colona versus "Echinochloa colonum" (Poaceae). Taxon 58(4): 1366-1368.
Verloove F. & Vandenberghe C. (1994) Nieuwe en interessante graan- en veevoederadventieven voor de Belgische en Noordfranse flora, hoofdzakelijk in 1993. Dumortiera 58-59: 44-59.
Ward D.B. (2005) A case of disputed orthography: is it Echinochloa colona; or is it Echinochloa colonum (Gramineae)? Sida, Contrib. Bot. 21: 2171-2183.