Citrus is a small genus of probably 16, predominantly Asian species (many more have been described). Many species are economically important and are widely grown for their edible fruits (lemon, citron, grapefruit, orange,…) in tropical and subtropical regions. Although much consumed in Belgium species of Citrus are only exceptionally found on dumps or river banks (from discarded kitchen waste). Citrus does not mature outdoors in Belgium and saplings are possibly not always recognized. Moreover, these are at most identifiable at generic level. Citrus saplings can be told by their glossy leathery leaves with winged petioles that are articulated at blade junction.
Citrus has been recorded from time to time since 1949, mostly on dumps or on river banks. Most recently observed on the banks of river Maas near Lanaken (Hochter Bampd) in 2012.
Gorman C. & Nelson E.C. (1997) Citrus. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 5. Cambridge University Press, Cambridge: 113-115.
Lloyd F. & Underwood L.M. (2001) Phylogenetic analyses of Aurantioideae (Rutaceae) based on non-coding plastid DNA sequences and phytochemical features. Pl. Biol. (Stuttgart) 3: 77-87.
Townsend C.C. (1968) Citrus. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 2. Cambridge University Press, Cambridge: 229-230.