In the environment of Mannheim Symphyotrichum lanceolatum is the most frequent of the daisies which have been introduced from North America and which ran wild.
The plants from the Mannheim Reissinsel (Fig. 7 - 19) have very big leaves, up to 15 cm lang and 3 cm wide, moreover they have a more dull surface than the glossy leaves of smaller-leaved Symphyotrichum lanceolatum plants. I'm not sure whether these plants can be assigned to Symphyotrichum lanceolatum in strict sense, too.