Cardamine hamiltonii G.Don, Gen. Hist.

Verloove, Filip & Ardenghi, Nicola M. G., 2015, New distributional records of non-native vascular plants in northern Italy, Natural History Sciences 2 (1), pp. 5-14 : 7-8

Cardamine hamiltonii G.Don, Gen. Hist. , 1: 167. 1831.

≡ Cardamine debilis D.Don, Prodr. Fl. Nepal.: 201. 1825, nom. illeg.

≡ Cardamine flexuosa With. subsp. debilis O.E.Schulz, Bot. Jahrb. Syst. , 32 (4): 478. 1903.

( Brassicaceae )

Naturalized neophyte new to the flora of Piemonte ( Conti et al., 2005; Celesti-Grapow et al., 2009a; Ardenghi & Mossini, 2014).

ITALY. Piemonte. Prov. Vercelli: Arborio, river Sesia N of the bridge, exposed river bank, 06.09.2014, F. Verloove 11043 ( BR) .

Cardamine hamiltonii is a poorly known but widely spread species in many parts of Europe. It has long been confused with C. flexuosa but molecular data have demonstrated that it is a distinct entity, apparently native in East Asia (e.g. Lihová et al., 2006; Bleeker et al., 2008). It is distinguished from the latter by the absence at flowering of a distinct basal rosette and the markedly trilobed leaflets that usually have a glabrous upper leaf surface (cfr. Mansanet-Salvador et al., 2015).

Al-Shehbaz et al. (2010) referred to this taxon as Cardamine flexuosa subsp. debilis but agreed that it should be recognized at species level and its correct name be sought. In recent times it became clear that the name C. hamiltonii probably can be applied for these plants (e.g. Bomble, 2014; Ardenghi et al., 2015; Dirkse et al., 2015).

For Italy this species was recently reported for the first time from Lombardia and Toscana ( Ardenghi & Mossini, 2014). In September 2014 it was seen in Arborio alongside river Sesia (see above), in an area from where it had been claimed before ( Dienst, 2007). It was also seen as an urban weed in Vercelli and in rice fields in Albano Vercellese and Robbio. It is well-established, weedy and doubtlessly widely overlooked elsewhere in Italy.