Thalia dealbata Fraser (N Am.) – A very rare escape from or relic of cultivation. First seen in 2015 in a small canal in Zonhoven. In 2016 also observed in a eutrophic lake in the Kalkense Meersen reserve in Berlare and in a pond in Lummen. In all these localities it may have been introduced on purpose initially.
Thalia dealbata is the only species of Marantaceae endemic to North America and the only one not found in the tropics (Kennedy 2000). It withstands 0-5°C or slightly colder provided the rhizome is submersed during winter. In suitable circumstances this species may grow very vigorously. A weed risk assessment showed that Thalia dealbata had invasive potential and was able to grow in most areas in China (Chen & Ding 2011, Wang & al. 2016). A moderate risk was estimated for the British Isles as well (Thomas 2010).
Selected literature:
Chen S. & Ding J.Q. (2011) Risk assessment and spread potential of alien wetland plant species Thalia dealbata in China. Plant Science Journal 29(6): 675-682.
Kennedy H. (2000) Marantaceae. In: Flora of North America Editorial Committee (ed.), Flora of North America, vol. 22: 315-319. Oxford University Press, New York-Oxford. [available online at: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10535]
Thomas S. (2010) Horizon-scanning for invasive non-native plants in Great Britain. Natural England Commissioned Reports, Number 053. [available online at: http://publications.naturalengland.org.uk/category/10006]
Wang H., Wang Q., Bowler P.A. & Xiong W. (2016) Invasive aquatic plants in China. Aquatic Invasions 11: 1-9. [available online at: http://www.aquaticinvasions.net/2016/issue1.html]