Bidens vulgatus Greene

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

Bidens vulgatus Greene , Pittonia , 4 (21): 72. 1899. [ Fig. 2 ]

( Asteraceae )

Naturalized neophyte new to the flora of Lombardia and Emilia-Romagna ( Conti et al., 2005; Celesti-Grapow et al., 2009a; Banfi & Galasso, 2010).

ITALY. Lombardia. Prov. Cremona: Casal- maggiore, river Po, damp track in woodland, lo- cally frequent, 14.09.2014, F. Verloove 11090 ( BR, MSNM); Prov. Pavia: Gambolò, Cascina Portalupa ( UTM ED 50: 32 T 495784.5013034), margine di sentiero in querco-carpineto, con Erigeron canadensis , Prunella vulgaris , Glechoma hederacea , 73 m, 17.10.2014, N. Ardenghi, P. Cauzzi & S. Pedrini ( MSNM); Prov. Pavia: Stradella, San Zeno, sponda destra del torrente Versa all’incirca all’altezza della rotonda tra viale Resistenza e la SP 201 ( UTM ED 50: 32 T 524108.4989963), vigneto, 86 m, 18.10.2014, N. Ardenghi ( MSNM); Prov. Milano: Milano, stazi- one FFSS di Milano-Rogoredo ( UTM ED 50: 32 T 518642.5031188), aiuola, 109 m, 28.11.2014, N. Ardenghi ( MSNM).

This is a widespread species in North America ( Strother & Weedon, 2006). Like the preceding, it is poorly known and overlooked in Europe, although known since many decades (e.g. Schumacher, 1941; Debray, 1963). Up to present it was known in Italy only from Friuli-Venezia Giulia ( Celesti-Grapow et al., 2009a). Bidens vulgatus is much reminiscent of B. frondosus L. but often more ro- bust with larger flower heads and with a higher number of calyculi (10-16 vs. usually 8).

In addition to the localities cited above, it was also detected along river Po in Boretto (Emilia-Romagna). It may have been widely overlooked elsewhere.

Figures

Fig. 2 - Bidens vulgatus, Martignana di Po (CR), September 2014 (Photo: F. Verloove).