Sisymbrium irio L. (Medit., W- and C-As., Macaronesia) – A very rare but increasing alien, possibly recently becoming naturalised locally. First recorded in the port of Antwerpen (Austruweel) in 1886 (few specimens in a road verge). Further rarely observed as a wool alien along river Vesdre, at least between 1936 and 1970. Exceptionally seen elsewhere but always ephemeral (Andrimont, Brussel, Sint-Idesbald,…). Discovered in 2001 in the city of Antwerpen (Zuid) and more or less persistent or locally naturalised since then (foot of walls, pavement weed, ground heaps,…). In the past years also occurring in other cities as an urban weed, for instance in Brussel and Mechelen but often ephemeral. Sisymbrium irio is also a characteristic weed in containers with olive trees from southern Europe (Hoste & al. 2009). In 2012 it was also recorded as a grain alien in the port of Gent.
Sisymbrium irio always grows in dry, sun-exposed habitats, exclusively in urban areas. Identical records are available from other northwestern European cities (see for instance Denters 2004).
Denters T. (2004) Stadsplanten. Veldgids voor de stad. Fontaine Uitgevers, ‘s-Graveland: 432 p.
Hoste I., Verloove F., Nagels C., Andriessen L. & Lambinon J. (2009) De adventievenflora van in België ingevoerde mediterrane containerplanten. Dumortiera 97: 1-16.
Langer A. (1995) Verbreitung und Vergesellschaftung von Chenopodium botrys L., Corispermum leptopterum (Aschers.) Iljin, Atriplex nitens Schkuhr und Sisymbrium irio L. auf Straßenstandorten in Berlin. Schriftenreihe für Vegetationskunde 27: 153-159.