Symphyotrichum pilosum (Willd.) G.L.Nesom var. pringlei (A.Gray) G.L.Nesom, Phytologia

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 : 12

Symphyotrichum pilosum (Willd.) G.L.Nesom var. pringlei (A.Gray) G.L.Nesom, Phytologia , 77 (1994, 3): 289. 1995.

( Asteraceae )

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

ITALY. Piemonte. Prov. Vercelli: Ghislarengo , ca. 1.5 km SW of the village, abandoned gravel pit, common, 06.09.2014, F. Verloove 10985 ( BR, MSNM) .

Symphyotrichum pilosum is native in eastern North America ( Brouillet et al., 2006) but widely cultivated as an ornamental in Europe. It is a poorly known species that has been confused with S. ericoides ( L.) G. L.Nesom, S. lateriflorum ( L.) Á.Löve & D.Löve and even S. lanceolatum (Willd.) G.L.Nesom. Italian claims of the first two species are mostly erroneous and referable to S. pilosum ( Banfi & Galasso, 2010) . The latter is fairly characteristic in having pedicels with numerous linear to subulate bracts and phyllaries with acute, spinulose apices. Stems and leaves may be either pilose to hirsute ( var. pilosum ) or glabrous ( var. pringlei ).

In Italy Symphyotrichum pilosum was only known with certainty from Lombardia ( Banfi & Galasso, 2010) although it may have been overlooked elsewhere. In Ghislarengo it has invaded rough ground in an abandoned quarry. It looks perfectly established there.