Psephellus dealbatus (Willd.) K. Koch (syn.: Centaurea dealbata Willd.) (Caucasus) – An exceptional escape from cultivation. Probably recorded only twice. First documented from the Albertcanal near Schoten where Psephellus dealbatus persisted for some time, at least between 1944 and 1949. In 2013 also discovered alongside river Sambre in Charleroi (confirmed in 2014; comm. M. Lannoy).
This species is characterized by its lower leaves that are distinctly bicolourous (green above and whitish tomentose beneath), its involucre 30-40 mm across and nearly orbicular appendages.
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