Dracocephalum thymiflorum L. (SE Eur., C As.) – A very rare and ephemeral alien. Recorded at the end of the 19th century as wool and seed alien (Verloove 2006). In 2017 a single individual was observed in the Ghent port area, probably as grain alien.
Dracocephalum thymiflorum is a weedy species that is often observed outside of its native range. However, it is now much less frequently introduced than it used to be formerly (e.g. Clement & Foster 1994). At present, it is most frequently dispersed via railway infrastructure, as a contaminant in crops and cereals, especially in eastern Europe (e.g. Jehlík & Dostálek 2008, Urbisz 2011, Rutkovska & al. 2013, Pliszko 2014).
This species is called Dracocephalum trifolium L. in Flora Gallica (Tison & de Foucault 2014).
Selected literature:
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
Fasset N.C. (1941) Dracocephalum thymiflorum in Ontario. Torreya 41(2): 57.
Fletcher E.F. (1911) Dracocephalum thymiflorum a casual Plant at Westford, Massachusetts. Rhodora 13(154): 212. [available online at: http://www.biodiversitylibrary.org/item/14484#page/221/mode/1up]
Jehlík V. & Dostálek J. (2008) Influence of railway transport in the South-East of Slovakia on formation of adventive flora in Central Europe. Biodiversity Research and Conservation 11-12: 27-32. [available online at: www.brc.amu.edu.pl]
Pliszko A. (2014) A new Polish record of Dracocephalum thymiflorum. Bot. Lithuanica 20(1): 64–66. [available online at: https://www.degruyter.com/downloadpdf/j/botlit.2014.20.issue-1/botlit-20...
Rutkovska S., Pučka I., Evarts-Bunders P. & Paidere J. (2013) The role of railway lines in the distribution of alien plant species in the territory of Daugavpils City (Latvia). Estonian Journal of Ecology 62(3): 212-225. [available online at: http://www.kirj.ee/public/Ecology/2013/issue_3/ecol-2013-3-212-225.pdf]
Tison J.-M. & de Foucault B. (coord.) 2014) Flora Gallica. Flore de France. Editions Biotope, Mèze : xx + 1196 p.
Urbisz A. (2011) Occurrence of temporarily-introduced alien plant species (ephemerophytes) in Poland – scale and assessment of the phenomenon. Katowice.
Verloove F. (2006) Catalogue of neophytes in Belgium (1800-2005). Scripta Botanica Belgica 39: 89 p. [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/tabel_2.pdf]