Some months ago I put some potting compost and gravel and water in a table jug to see if I could keep some rotala rotundifolia alive long enough to replant. It was wrapped in a mystery plant. I left it in a sunny window, algae came and then went and a ramshorn snail hitcher found it tolerable. The rotala has survived and the mysterious plant turned out to be a delicate carnivorous bladderwort. This week it started to flower.