I mislabelled the plants and grew them as B. filifolia in moist LFS. They are now flowering at the height of 6cm and THEN I realise that they are actually the aquatic species.
The flowers do not open fully in my conditions.
The seeds were labelled as "copper coloured stems up to 20cm tall".
Dark purple petals
Compared with mauve/lilac B. filifolia petal
Anther cf filament length