Helianthus grosseserratus M. Martens was first recorded in Lithuania in 2014. Rather large population of this species was found in Siauliai district (northern Lithuania), in the vicinity of Bridai village, on the territory of recultivated former municipal dump. This species can be easily distinguished from other perennial Helianthus species by glabrous stem, long, serrate, alternate leaves on the upper part of the stem and spindle-shaped roots. Supposedly, H. grosseserratus was brought to the area with garden waste or soil used for dump recultivation about 30 years ago and recently it has established in the locality. In the investigated capitula, no developed seeds were found. H. grosseserratus reproduces vegetatively by rhizomes and under favourable conditions can survive for a long time.
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