NATIVE RANGE: North America

FIRST FINDING IN SLOVENIA: 1840

PATHWAYS: hitchiker, secondary seeds are spreading with the wind

POSSIBLE TO FIND: year-round

FLOWERING SEASON: May – October

DESCRIPTION: Annual, or often bi-annual herbaceous plant with an erect, branching, pillose stem. Leaves are light green, pillose on both sides. Lower leaves obovate, with petioles, up to 10 cm long. Upper leaves are lanceolate to linear, with entire to serrated margins, up to 9 cm long and 2 cm wide. White to pink ray florets and yellow disc florets together form 15–20 mm wide flower heads. Achenes are 1–1.5 mm long with hairy tufts.

HABITAT: Irregularly mown meadows, fields, abandoned arable fields, ruderal sites, gravel banks, road edges and lawns.

STATUS: Widespread all over Europe. In Slovenia found throughout the country but only exceptionally above 1000 m a.s.l. in the mountains. 

SIMILAR SPECIES: Among the alien asters with white ray florets, panicled aster (S. lanceolatum) and Tradescant’s aster (S. tradescantii) also occur in Europe. These species can be distinguished by leaf shape, the number of ray florets and the placement and colour of the involucral bracts (see drawings on the right). European native scentless chamomile (Matricaria perforata) has similar flower heads, but leaves are pinnately compound with narrow linear leaflets.

SOURCE: Field Guide to Invasive Alien Species in European Forests