**6. Conclusions**

Thus, the obtained data on hybrid activity among the Asteraceae family of invasive species are ambiguous.

Hybrid *B. decipiens* has a low polymorphism. *B. cernua* is the most polymorphic taxon, and we can assume the presence of introgressive hybridization of *B. decipiens* with a maternal species. The analysis of ITS1-ITS2 and trnL-trnF sequences showed that *B. decipiens* is of hybrid origin and its maternal form is an aboriginal sequence of *B. cernua* and the paternal one is probably invasive *B. frondosa*. It is possible that *B. decipiens* in its present form has already appeared by introgression, but no morphological differences between supposed hybrids (Belarusian and Kaluga plants) and supposed backcrosses (plants from Moscow and Kaliningrad region) have been revealed. It should be noted that *B. frondosa* itself may be of hybrid origin.

In the northwest of Russia, the populations of three taxa of *Solidago* genus—an invasive species of North American origin of *S. canadensis*, an indigenous species of *S. virgaurea*, and their hybrid *S. niederederi—*grow together in the vicinity of the city of Pskov, which was confirmed by the sequence analysis of the ITS1-ITS2 site. Since both parents, especially *S. canadensis*, are quite polymorphic taxa, it is impossible to answer unambiguously which of the two species is maternal and which is paternal.

In Southern Europe, the hybriogenic activity of representatives of the genus *Erigeron* is close to zero. The low hybriogenic activity can also be explained by differences in the chromosome set: in *E. canadensis* 2n = 18 and in *E. sumatrensis* 2n = 54 [32].

Our data on the rare occurrence of hybrids in comparison with parental species in the Asteraceae family contradict the hypothesis explaining the success of plant growth in the new homeland by strengthening hybridization processes in the secondary distribution range [1, 2], but this situation may change in the coming decades, so the hybriogenic activity of invasive species requires attention of the scientific community.

## **Acknowledgements**

This study was carried out with partial support from the Russian Foundation for Basic Research, grant no. 18-04-00411.

**Author details**

**109**

Maria A. Galkina\* and Yulia K. Vinogradova

*Hybridogenic Activity of Invasive Species of Asteraceae DOI: http://dx.doi.org/10.5772/intechopen.91370*

provided the original work is properly cited.

\*Address all correspondence to: mawa.galkina@gmail.com

N.V. Tsitsin Main Botanical Garden, Russian Academy of Sciences, Moscow, Russia

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,
