Isotoma axillaris Lindl. (syn.: Laurentia axillaris (Lindl.) E. Wimm.) (Australia) – A rare and probably ephemeral escape from cultivation in urban habitats. Since 2018 discovered in several localities in the cities of Antwerp and Brugge (and doubtlessly overlooked elsewhere since flowers are not always observed). Plants always grow on pavement in cracks of concrete, foot of walls and similar habitats.
Isotoma axillaris is much grown as an ornamental these days and apparently easily reproduces from seed. Its flowers are less obviously zygomorphic than in similar-looking species of Lobelia (incl. Pratia). Based on its irregularly pinnatifid leaves it cannot be mistaken for any other lobelioid species currently found in Belgium.
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