Panicum barbipulvinatum Nash, Mem.

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 : 8-9

Panicum barbipulvinatum Nash, Mem. New York Bot. Gard., 1: 21. 1900.

= P. riparium H.Scholz, Feddes Repert. , 113 (3-4): 275. 2002.

( Poaceae )

Naturalized neophyte new to the flora of Italy (Piemon- te) ( Conti et al., 2005; Celesti-Grapow et al., 2009a).

ITALY. Piemonte. Prov. Alessandria: Valenza, riv- er Po S of the bridge, sandy river bank, very common, 07.09.2014, F. Verloove 11060 ( BR); Prov. Alessandria: Arquata Scrivia, river Scrivia N of the bridge, gravel- ly river bed, frequent, 09.09.2014, F. Verloove 11062 ( BR) .

Panicum barbipulvinatum is an enigmatic species originating in temperate North America. Its taxonomic status is debated: in its area of origin it is merely included in the variability of P. capillare L. by modern authors (e.g. Freckmann & Lelong, 2003). In Europe, however, where only part of the genetic diversity of the latter is present, it is easily distinguished. This inspired Scholz (2002) to describe it as a neo-endemic species new to science, P. riparium . Recently, Amarell (2013) demonstrated that Scholz’ new species in fact perfectly corresponds with the American P. barbipulvinatum . Moreover, he advocated, like Scholz, that this taxon should be accepted at species rank (as is, for instance, P. hillmanii Chase from the same species complex). His point of view was followed in the recently published Flora Gallica ( Tison & de Foucault, 2014).

Panicum barbipulvinatum has a laxer inflorescence with spikelets on short pedicels that are tightly appressed. The narrower spikelets are long-acuminate at apex. This particular combination of features renders the plant a characteristic jizz that is fairly different from that of P. capillare .

In September 2014 Panicum barbipulvinatum was seen on several occasions in Piemonte, always on ex- posed sandy or gravelly banks of rivers Po and Scriv- ia .