In most of its features, this plant closely resembles Water-cress (Nasturtium officinale) but it has two main features which distinguish it from that plant. The rich, shiny, pinnate dark-green leaves tend to turn bronze-purple in autumn which is one of the main aids to identification of this plant. Also, the longer, seedpods only contain one row of seeds, unlike those of Water-cress which bear a double row of seeds. White, 4-petalled flowers (4-6 mm) are borne in clusters on erect stems from May to October, remaining a little later than those of Water-cress. It is a creeping plant which tends to grow in acidic soil and close to damp watercourses. This is a native plant and belongs to the Brassicaceae family.
I first recorded and photographed this plant in New Ross, County Wexford in 2011 when Paul Green, BSBI’s Vice-County Recorder for Counties Waterford and Wexford, pointed it out to me.
If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre