Lobelia siphilitica (blue cardinal flower) has stunning spikes of beautiful lavender-blue flowers on light green foliage. It flowers from August to September just as some of the other pond plants are starting to fade, and is a great source of nectar for bees late in the season. The unfortunate name is derived from the fact that it was used to treat syphilis!
Lobelia after Matthias de Lobel plant collector and botanical author
Planting position: Marginal plant up to 5cm full sun or partial shade.